• It is instantly familiar in operation to anyone who has used Twitter. It looks and feels almost the same to use in a way that Mastadon doesn't (arguable whether that's a good thing or not, but it makes for a comfortable transition).

Yup, pretty much. I tried Mastodon and found it very unintuitive, but BlueSky was immediately understandable as a former Twitter user. I don't really use either that much, but I've spent way more time with BlueSky.

Honestly, it's the same with Lemmy. I tried a lot of Reddit alternatives, both federated and centralized, and I landed on Lemmy because A) It has the only decently-sized user base and B) my preferred Reddit app, Sync, moved to Lemmy. Lemmy is similar enough to Reddit on it's own that transitioning over wouldn't have been difficult, but having Sync just made it that much easier.