What's the error? I'd hyphenate "poorly-composed" (most wouldn't these days, but they can go to hell) and I think it's a bit too wordy for what it's communicating, but I don't see what I'd call an actual error.
I would personally avoid writing that "poorly composed sentences" have an "affect"—rather than the writer having or presenting an affect, or the sentences' tone being affected—as I find an implied anthropomorphizing of "sentences" in that usage, which anthropomorphizing isn't serving enough useful purpose, to my eye, that I'd want it in my writing, but I'm not sure I'd call that an error either.
What did you mean?
> Commas and parentheses can do it all, and an excess of either is a sign of poorly edited prose.
This attitude, however, is a disease of modern English literacy.