To answer the headline, nothing happened to it. Writing about stuff for writings sake and just to get it out of your head into some form is still very much a thing. That said, it is possible to make (varying amounts) of money writing a blog, and so it attracted a huge number of people who wanted to do that, and as a ready market various "corpo" types sprung up to "feed their dreams" for a small fee. And this is where the disaster happens.

When companies that index the web make 99.9% of their money selling ads on that index, and the index is a place where wannabes ask the question "how do I make money on a blog" ask that question, you gets something not unlike unconstrained algae growth in a badly maintained aquarium of things "popping out of the woodwork" to fill that demand. As a result, if you used that to measure "What happened" you would easily come to the conclusion that nobody does this any more, after all wouldn't it be great to have a reliable way to "collect" the blogs of interest and be notified that they had said something new?

Yeah, that would be a really cool thing but apparently the corpo types could not figure out any way to make money on that and so decided to cancel that part of their offering.

Yes, I'm still mad about it :-)