Comment by manigandham

1) JS history handling is fragile. A single error can break navigation completely. There's no built-in loading indicator so sites are left with no feedback or have bloated progress bars. And nothing automatically solves for deep links if the app doesn't use routes for different views or relies on other events instead of hyperlinks.

2) Servers are very fast and assembling HTML is trivial. Browsers are optimized for downloading, parsing and rendering HTML as it streams in. Using JS to write HTML after making multiple network calls is objectively slower than a single network request that assembles everything on the server close to the datastore with minimal latency.

3) Every other language is faster and more capable on the server than JS, and all major web frameworks have modern component-based UI templating. Interactions with roundtrips are just fine, and some light JS can handle most other scenarios.

> "an actual application"

That's the only reason to use a SPA, not what you mentioned.