"Server-side rendering is not a fallback; client-side rendering is an enhancement."

I would further and say client-side rendering can be (not "is"), a performance optimization for subsequent page loads (and offline). It's only a net-win if you invest non-trivial effort (SW, streams, race network, handle long-lived tabs and cache misses to old JS, etc).

In almost all other cases, it merely produces a slower, less usable, less available version of itself.

by @adactio

https://adactio.com/journal/9963