Okay, I'm going to give you a shotgun blast of these and a good chunk of them may just be wrong. (It's my birthday, I feel crotchety, so out comes the red ink) If I were close-reading a text for an important purpose, here are the things I'd want to bring to the author's attention:
* "as easily remedied" seems to be an orphaned comparison to a parallel structure in an early paragraph that's been removed? At least, that's the way I can make it make most sense. As it stands: as easily remedied as what?
* "With genres such as “speculative fiction” that used to be for comics and cranks now taken seriously, and made-up genres like psycho-geography and ethnography sprouting all the time, not to mention the world’s back catalogue being available on one’s phone (and of course on-line titles like The Critic spewing essential verbiage like a broken main into the thoroughfare of discourse 24 hours a day), it is quite impossible to keep up or even to tread water." A decent editor doesn't let this sentence see the light of print. Even setting aside the Gish gallop of off-topic contrarian dinner-party remarks, you just... don't need that broken main simile. In a sentence that long, you just don't have the breath to spend.
* "maintaining well-articulated and informed opinions becomes ever more demanding on our time" Well-articulated has to do with writing rather than reading, and surely it's "demanding of" not "demanding on"? That latter would be one I'm trying to assume is a Briticism.
* "The diagnosis focuses on posited aromatic chemicals in ink or the ominous quiet that predominates and subconsciously reminds us of exam halls." "Predominates" is clear enough used on its own, but in this place in the structure, it almost seems like it's being applied transitively to "exam halls".
* "Now, over ten trillion new titles[...]" "Some, we’ve read." Not all ungrammatical conversational structures are bad, but those commas are just odd in places where the reading is far clearer without them. It's as if the advice that in English one should read a comma aloud with a pause had been taken as a bijective map...
* "When I mentioned the theme of this piece, for instance, my daughter immediately and shamelessly confessed to having recently completed an English essay on a text that she hadn’t even opened, based purely on the class discussion that she had attended on the first day back after a week off with Covid." Just split it into two sentences! It doesn't all have to go in one!
* "I affected to look disapproving but this, I venture, may well prove a more valuable skill set than the one ostensibly being tested." The "this" would naturally bind to "affected to look disapproving" without the object of the disapproval featuring somewhere in the first independent clause.
* "Students have long speculated whether the York Notes couldn’t tell them all there was to know about Crime and Punishment." I can't figure out why "couldn't" is there in the negative, since "whether" normally implies both positive and negative options.
* "Nowadays even that level of investment, financial and temporal, is unnecessary." Commas don't set this off enough from the rest of the sentence, so it doesn't read smoothly that "financial and temporal" applies to "investment" rather than "level".
* "one from say, the LRB or Prospect, just so you know what Lefty nonsense someone is likely to spout;" Given all the little asides set off with pairs of commas in this piece, how was the comma between "from" and "say" missed? Similarly, "There are thousands of these of course, but Amazon has" seems to be missing a comma between "these" and "of".
* "Pair this with the first twenty pages of the book itself, downloaded as a free Kindle “sample”, to familiarise oneself with the author’s stated intentions and stylistic irregularities and you are in a better place[...]" You can use a general "you", and you can use "one" for the same purpose, but to use both in the same sentence is sloppy as hell.
* If they're not using the serial comma, is it normal to still include a serial semicolon in the same place? Honest question.
* "It indicates an insightful, often amusing and pithy contribution — certainly pithier than the books that now emerge from the industrial bread-making approach taken by modern publishing, to get a decent magazine article up to 100,000 words." What are we to make of the comma after "publishing"? If the "to get a [...]" chunk was meant to attach to the "contribution", wouldn't the comma instead be another dash? If it's meant to attach to "approach", why is it there at all?
* "Once you’ve read the “Helpful” reviews, if you want to be really bulletproof, scan the three- and four-stars too." This is garden pathy (https://en.wikipedia.org/wiki/Garden-path_sentence) verging on ambiguously structured. Imagine you read just this sentence with the "too" chopped off. You wouldn't be able to tell whether "if you want to be really bulletproof" applies to "[reading]" the 'Helpful' reviews" or to "[scanning] the three- and four-stars too." One can understand it in context and with the "too", but the sentence feels clunky because the structure doesn't reflect its logic clearly.
* "Besides, if it weren’t for quotation books I doubt many of us would know Ralph Waldo from Fitipaldi, Almieri dos Santos or Keith." Why no comma to set off the counterfactual conditional? If the piece were generally written comma-light, I'd get it, but...
* "[...]currently struggling through — I wonder if you have already[...]" Is it a British thing to not use a semicolon in this kind of construction?
* "Books continue to flourish as a commodity, but to other purposes: as vectors of conversation, signalling and setters of agenda." "To other purposes" is unnatural but obviously permissible a la "to what purpose". In terms of the content, when people talk about books being a commodity, they're typically already contrasting that with "books are for reading." Also, the sequence there is uncomfortably close to a parallel structure but doesn't make it. "[...]as vectors of conversation, signals of X and setters of agenda" would read nicely, but you can almost get "as vectors of conversation, as vectors of signalling and as vectors of setters of agenda" from how the existing version parses out expanded.
* "Writing a book is mainly about conferring a degree of status on the author, getting her invited to literary festivals and onto Front Row." Said aloud it'd be fine, but that "getting [...]" just hangs off the sentence.
* "My physical bookshelves are double stacked, with a row of books who once had the shelves to themselves, now entirely obscured by new arrivals, like an unwelcome development spoiling their view." This sentence is structurally mushy. "My Xes are Y, with a Z who A to themselves, now B by C, like a D Eing their F." Even if we forgive the aroma of comma splice unseen, the pronoun resolution here is a mess.
* "A sort of three-dimensional version of the “palimpsest” that is well known to anyone who pretended to have read The Name of the Rose before seeing the movie adaptation." And here we give up on connecting way-too-many-clauses with commas and send a subject off into the world to survive sans predicate.
* "Meanwhile, I have some 2500 books in my kindle library, the vast majority unread. My Kindle library, incidentally, can be arranged in order of purchases." Even the worst editors correct Brand Capitalization, and here the author hasn't even bothered to match. (Also weird not to have a comma in that "2500" in the style I'd assume of this kind of publication, but it might be a choice)
* "Tellingly the first download was The Complete Works of Shakespeare[...]" Tellingly, I see no comma, despite many other such initial adverbs in the piece being given commas...
Anyway, this is on the editor (or absence of editor). There's very little here that I'd think the author should feel bad for not catching. Writing and rewriting your own prose – especially reading it aloud to yourself with the inflection you intend – numbs the eyeballs to many such things.