I believe it's often because nobody does their own website anymore but instead uses managed services, e.g. Medium. Or bits of information, that would've been worth a blog post some while ago, end up on sites like StackOverflow, Reddit, etc.. And once these services want to monetise these contents, they usually start with limiting public access.

And OTOH TikTok, Instagram Reels and YouTube Shorts are doing everything they can to further limit people's attention spans and get them addicted to those services. So the people capable of and/or interested in producing proper "content" are dwindling, too.