I think a lot of what used to go onto blogs now goes elsewhere, but doesn't necessarily stay bottled up in the mind of the would-have-been blogger. Even while pseudo-blogging platforms like Substack are having something of an upswing of esoteric low-audience content.
And I can say from experience that it's tough keeping a blog going when you have near-zero readership, even if you still consider the act of writing something and putting it out in public to be instrinsically valuable to you.
Just as a simple example, I have a once-in-a-while newsletter+blog on a niche topic, and I could get way more eyeballs if I'd just rephrase things as a Reddit post, but I'm nostalgic about it living its own life on the Free-ish Web. Or, I suppose, this comment right here, which could just as well be on a personal blog with a "backlink" to yours.