ultracycling!
So since Bluesky assumes that most users want to see posts by strangers chosen by some sort of algorithm, which picks them out of the entire pool of content on the platform, then, well, you need the entire pool of content on the platform to pick posts from. Hence the unwieldy "shared heap" architecture. ActivityPub's publish-subscribe approach would've been a serious nuisance if you were to build such a product on top of it.
@grishka conveniently, that also makes advertising a lot easier, and raise the bar of competition much higher.
Hard to say it’s bad, after all they are just delivering to what people ask for. Today, we are spoiled by the endless feed, and increasingly comfortable with being profiled by algorithms (instead of talking about hobbies, many ask each others “what’s your algorithms”).