Steam/valve also does a lot of things that everyone benefits from. Amazing controller support, Proton, etc.
Even some minor things like allowing p2p games to route through their servers so players IPs aren't shown to others
For everyone else though, it's like digital crack. It was the place to be for a while, even though it's users would chafe over minor changes. And of course, there was the original Cambrian explosion of microblogging movies and blind dates and garage sales and haircuts et. al... mostly replaced today by politics and related vitriol.
It's 100% the fact that there is no meaningful competitor, exacerbated by people being lazy and distrustful of other private platforms. And good - these people should be wary, and Cory Doctorow should be on his soapbox telling people how to live in a post-social-media world rather than riling them up to go yell at clouds online.
I'm not sure Twitter ever was a universal thing. I barely know any people in real life that actually use it. It's only tech nerds/people working in media, and the others don't exist in real life because they don't go outside. It's easy to ignore Twitter drama completely, because nobody cares about Twitter except the people that use Twitter.
Instagram and TikTok however really did capture the mainstream.
I'll agree on Steam - it has its problems, but the users, as a rule of thumb, don't hate it. It works, its reasonably convenient, most users don't get burnt by its policies, and nobody wants to install crap like Origin and UPlay.