it's not, because phone coverage can be spotty when in a car using the train, busy wifi connections etc. aren't we supposed to be optimizing for mobile? SPAs should only be used for things like gmail. Newspapers offering megabytes of javascript , when they know that a lot of their reading happens in trains is obscene.

On the one hand google promotes SPA frameworks. on the other hand , google makes AMP because they are too slow. It's not stated often enough, but modern web is schizophrenic