One is that most people consume content in apps, so most creators create contents for that audience. TikTok, Twitter, Reddit, Facebook, YouTube, etc are where users are, so it's where creators put their content for visibility. Related to this is, I feel, the switch to mobile, where the more limited UX of the device makes it a LOT easier to just stay in the same app rather than type URLs or manage a ton of bookmarks. For many people who weren't computer literate in the 2000s, they find apps on their phone MUCH easier to use than a browser with mouse/keyboard.
The other is the huge rise of SEO spam sites. They dilute search results and waste time. Combined with the first point, there's now far less signal and far more noise than ever, so often looking for websites isn't fruitful. This creates the feedback loop: users aren't looking for websites, so why create content on websites?
EDIT: I'll add that I often think of StumbleUpon, which my friends and I really enjoyed using around 2010. It was enjoyable clicking a button and being taken to a random page on the Internet: a funny video, a deep dive on WW2, a quirky page devoted to someone's pet tarantula. The variety of topics and experiences you would encounter were much broader than what you'd see today, where most content follows the same patterns to achieve success for its respective platform. StumbleUpon could not be successful today.