> Which streaming service do I go to now for the science fiction?

Exactly. Every company has segmented their content by company, not by type. Sure, I can buy a subscription to Boomerang and get a lot of cartoons, but it's just the cartoons owned by Warner. But not all of them, because they've moved some of them--like Dexter's Laboratory--off to be HBO Max exclusives.

There's no way to say "I want a science fiction themed service" that includes Paramount and HBO and the old PTEN and the like, because no company would stand for another service mixing their IP like that.