This was my thought, too. In reality, client side rendering today is “cheap” because you typically put a CDN in front of your application to serve static resources and scripts, and your backend only serves the API requests (if needed). Rendering everything on the backend means by contrast that you’re limited to the capacity of your server and the latency based on where it’s located.
Counter-point to this is that edge computing addresses the latency for compute in the same way that a CDN does for static assets.
SSR definitely has drawbacks in the old "run your app from a single VPS somewhere" model, but in a globally distributed edge computing model, you remove a lot (but not all) of those drawbacks.
