The fundamental difference is in the public: extreme-left for bluesky, trumpist for truth social and twitter for whoever isn't making a platform choice part of its identity.

The extreme left are on small mastodon servers and hate BlueSky and the large mastodon servers almost as much as X at this stage. Given Elon's control of the platform, manipulation of the algorithm and petty bans, it's been a while since X/Twitter has been a neutral choice. What's left of it is certainly at least as right wing as Bluesky is left.

I haven't seen anything remotely "extreme-left" on bluesky. I have seen swathes of racist, objectionable, far-right nonsense on X, though.

until it changes that

What's the point of posting on those platforms? Self-promotion and PR. The difference you highlight is very superficial and ultimately it is the same thing.

The difference is your audience. Are you talking to people you know or are you talking to 'the world'. If I'm talking to a bunch of my friends in the pub, I don't consider that "self-promotion". If I'm stood on the street corner saying exactly the same kind of things, it would be. In fact, that means I think that posting a comment on Hacker News is more self-promotion than posting a comment on Bluesky. Which I do.

If you want to talk to people you know you have apps like Whatsapp. Bluesky is to talk to the world one way or another and so is the same as Twitter ultimately even if for the time being you may be able to filter what you see more.

I mean, just now I went to Bluesky's web homepage and what I saw is "discover" pointing me to "influencers"...