Why do you say DMs are by far the most important feature? Lots of other services provide DMs besides Twitter, and I would not say it is the key thing that makes Twitter what it is. At least for myself, in a dozen years on the platform I used DMs only a small handful of times.
Maybe this is different depending on what industry you're in - but for a lot of people in my circle (tech/startup media), the incredible thing about Twitter is that you can DM almost anyone.
I've connected with so many people there.
There's also a culture of DMing there, where your messages have a higher likelihood of getting replied to than other places like LinkedIn.
I didn't use DMs for years. And also wasn't a big Twitter person at all. So I get it. But that all changed a few years ago, and now, I'm tellin ya' - the only feature that matters there is the DMs.
See, this is the fascinating thing about Twitter; it's so incredibly compartmentalised (or at least _was_; as another article posted here recently went into some detail on, recent changes have tended to break this). I had no idea this was even a thing; in my former Twitter circles this behaviour (unsolicited) would've largely been considered pretty rude, and in any case it's not clear why anyone would want to do it.
