Facebook and microblogs use the same infra and can be accessed via the same means (web browser, etc).
At least from anecdotal experience, the really good stuff has been getting easier to find through IRL-ish means, like asking a colleague for the invite link.
I haven't really seen behind the invite veil much, since I'm about as far as it gets from someone cool you'd want in your group chat, but from what I've seen, "good" things are happening and thoughts are thought. It's just happening in private.
There were comments or an article somewhere about someone being sad about "very deep technical discussions being held on discord servers and that knowledge being ultimately lost". I don't think it's that bad of a thing though since that knowledge was never intended for the public and being ultimately lost and forgotten is what the people writing said messages are expecting of it. Certainly, as a person, I care more about myself having less of a digital papertrail than someone in the indefinite future not being able to solve their nieche non-essential problem.
I could elaborate more on the "onlyfans has replaced sex" and the such, which are, IMO, while somewhat true, are conclusions to which the author arrived to from a wrong place, thus continuing to think in that direcion would get them further from the truth, not closer to it.
In the end, just as human brain is a sort of general purpose multimodal input-output machine, the internet can be used for all sorts of purposes. The good ones will stay, the bad ones will fall out of fashion, without getting a solid cultutal foothold. The test of time works as well as ever.