There's definitely trade-offs. I actually prefer a proper SPA to pure HTML when on a slow connection and interacting with a site a lot.

Especially when trying to buy something. I much prefer to have a longer initial load and then have everything just work instead of waiting as I navigate between pages, the multi stage checkout, confirmation etc.

But yeah, if I'm just trying read a single article on a blog, preloading everything is pointless. A hybrid site with the initial page being server side rendered + progressive enhancement afterwards is theoretically optimal in my opinion.