As far as I'm concerned you want to use a SPA when you have dynamic interlinked state. None of these sites have that. You give up so much simplicity going to SPA its kinda crazy and again I say that as a person who loves Svelte but I think is only necessary for occasional core pages.
But I constantly doubt myself, I must be missing something? Maybe its just easier for large orgs with dedicated frontend/backend devs but it really doesn't seem efficient.
The ability to press back on tutorials is incredibly useful. And the site seems unnecessarily slowed down by SPA. There's nothing here that needs a SPA besides logging in and gamifying that you completed a tutorial.
Orange warriors: endgame