I wasn't here in 2018, but I was on Medium in 2020 and I would say that most people have moved on because the pay was terrible. $15 was my best month back then.

AI wasn't around, but a lot of the writing was really bad and they had even more click-bait articles. Also, plagiarism was much more common than now, as most just use AI.

Medium has a lot of issues and it's not perfect but it's much better now than it was back in those days.