I'm sure there are people much better qualified to answer this than me but it feels like there would be a point at which trying to manage a very complex UI with all these little HTML fragments over the wire would get unmanageable. I'm just guessing though. So far I haven't done anything that complex with it. I guess I'd also miss having Typescript for a UI with a lot of components.

You can do some client-side state management with Stimulus though.