A few trends over the last two decades:
* targeted monetization of everything under the sun
* a total shift towards a subscription economy for nearly everything digital.
* a near total shift towards mobile content consumption devices especially for younger consumers (tablets and phones)
has likely resulted in the following:
* low quality algorithmically driven junk food content (tiktok, instagram reels, the garbage people post to advice subreddits)
* startups j-curving for usage and leaning into advertising as their only viable business case
* Google scraping your inbox for ad keywords in the mid 2000s and beyond, Microsoft injecting ads into Windows 10 and 11, etc.
Perhaps worse:
* Generation Alpha and later Gen Z kids having relatively diminished technical literacy compared to elder Gen Z and Millenials (absolutely anecdotal. I'm citing three teacher friends frustrated that kids navigate their way around computers more poorly with each passing year)
* subconscious mass influence of behavior patterns (foreign election interference, your trip to your local McDonald's, sneaker hype culture)
Practically the only thing that hasn't actually gotten worse online, regardless of our own diverse opinions about it, is Wikipedia. It's a for-profit warzone of competing interests making competing edits, but it's an example of what can happen when the constant growth/profit/exit-motive isn't there.
Many of the hobbyist sites running on sites like vbulletin or invision are gone; we use subreddits for those now. And people don't even bother with those, more and more people just post meme gifs in the comments of reels, sitting there scrolling through with their thumbs rather than contributing something new and unique.