I've come to the opinion that for the vast majority of apps I've built, it could all be built using HTML + CSS (all built server side). I can sprinkle in little bits of interactivity using something like HTMX. And I'll have a website that is very easy to optimise, has phenomenal backwards compatibility, and gets rid of a whole class of issues associated with SPAs.
I often regret in my career not pushing back more on "requirements" that ended up requiring a more complicated app, whereas the customer would have been happier with a simpler solution.