I don't think it was forgotten, it was considered irrelevant by FB/Meta and TwX because they were more interested in collecting information about social graphs

I don't think it was forgotten, it was considered irrelevant by FB/Meta and TwX because they were more interested in collecting information about social graphs and demographics so they could sell ads and influence. So they invented (copied) following/friending individuals, which was the opposite of USENET's newsgroup (topic) system and also (sadly...) a proxy for social status. In reality there's always been huge interest in topic media. Reddit sort-of owned the space for non-real-time posting, and Twitter got some way there with lists for news and the breaking hashtags. BlueSky feels somewhere between those - still short posts (bad...), more topic than social graph, but not so obsessed with clout chasing and status.