> the idea of essentially removing the network round trip when a user clicks on something is not a bad one.
Practical SPA's have many more network roundtrips than the equivalent server-rendered web interface. Every AJAX request is an extra roundtrip, unless it can be handled in parallel with others in which case you're still dependent on the slowest request to complete. With SSR, you can take care of everything with a single GET and a single POST no matter what. Images load in parallel of course, but those are non-critical.
Practical SPA's have many more network roundtrips than the equivalent server-rendered web interface. Every AJAX request is an extra roundtrip, unless it can be handled in parallel with others in which case you're still dependent on the slowest request to complete. With SSR, you can take care of everything with a single GET and a single POST no matter what. Images load in parallel of course, but those are non-critical.