> - Streaming game primitives instead of pixels, which should be much lighter - Server-side rendering makes cheating basically impossible

This doesn't work in 3D. Unless you have the server do the work of the GPU and compute occlusion, you'll end up sending data to the client that they shouldn't be able to have (e.g. location of players and other objects behind walls)

Theoretically couldn’t you send each client its data after performing occlusion culling based on each one’s camera?

Don’t some competitive games more or less already do this? Not sending player A’s position to player B if the server determines player A is occluded from player B?

I seem to recall a blog post about Apex Legenda dealing with the issue of “leaker’s advantage” due to this type of culling, unless I’m just totally misremembering the subject.

Regardless, seems like it would work just fine even in 3D for the types of games where everyone has the same view more or less.