Is it that not enough have joined from Twitter or that the Twitter algorithm encourages interactions via likes etc whereas on Bluesky we only get one like if we are lucky and few comments and these are not broadcast?

Perhaps. IMO there’s also a behavioural difference. People here seem to bubble wrap everything. I’ve not yet witnessed an interesting intellectual confrontation. There’s a kind of fake facade of performative kindness to every interaction here

Hard to say, but on X I track only "following" which does not include algorithm posts (as far as I know).