Earlier quoted context omitted.
How do we know if "this level of speed and content online" is net good?
This really depends on the content you are seeking and consuming as the user. I am constantly pulling data sheets, reading papers, researching reference designs, interacting on official (and unofficial) product forums, and countless other information queries which at the start of my career were largely conducted at either company or university libraries, in person meetings, or attending conferences. That may sound gr…
So I'm confused as to why you think advertising has driven the development of the internet[1]. Take for example investments in bandwidth - that's largely to meet the needs of TV/video and later gaming [2] - both with direct revenue streams independent of advertising ( and any advertising revenue they traditionally got has been eroded, not enhanced by the internet ).
The other major sites where things like Amazon or existing media outlets.
Note I don't include youtube in the above - as the most popular content is in effect stolen ( music, old TV shows etc ), and then resold with ads.
[1] Internet companies yes, the internet less so.
[2] When BBC iplayer went live in the UK ( ~2007 ) ISPs complained that it was taking up to a third of their entire bandwidth and they wanted the BBC to fund their capacity expansion. The BBC said, nope - it's you that made you bandwidth availability promises to your customers.