https://developer.chrome.com/docs/web-platform/view-transiti...
Yeah, but it ain't. lol.
Users don't care how it was implemented or how nice the code looks, they just want it to work.
By your measure though, it sounds as though you'd be fine if these page loads in the javascriptless world were done in iframes, since then only some portion of the site is being reloaded?
I'm using that to illustrate the argument is absurd and the basis on which it is made seems also absurd.
SPAs are heavy and frequently written poorly, often eschewing the principles of loading only the bare minimum for a kitchen-sink approach. If you view the web as having only those two options to accomplish "real work" then yeah, you're gonna thing that SPAs are the only way. It's not reality though.
In my experience, these apps are rare, yet SPAs are prevalent. Which is a problem.
It would be nice, from a user perspective, if boring "apps" that are mainly forms and tables would quit it with SPAs already.
Making an entire application a single page load and then some API calls sounds attractive when your application is small to medium sized in terms of complexity. It runs into problems when complexity or feature count pass a certain point.