I'm not arguing with you, I think most SPAs are unjustified, it's just that 15/20 years ago people really wanted to get rid of whole page refresh and all the problems that brings, which is a laudable aim, but has morphed into "why don't we make our own back button" and nonsense like that.

The justification nowadays seems to be (in truth) "if you take away my tools I don't know how to build things so I'm going to run npm init and go from there".