It’s because the people that built and maintain the SPAs were beat into submission with the “SSR” bad message. Now people want them to do SSR again.
I agree. SSR that hydrates to an SPA is a pain in the butt and not necessary most of the time. This is why I favor something like Astro for websites... I can drop in a react embed when I need to. It's just a right-tool-for-the-right-job situation imo.
I absolutely love Astro, and it's my default for new projects. And I honestly feel like it's the only framework using React/Vue for their intended purposes; which is as an interactive layer on top of your SSR UI.
You're kind of already answering your own statement; websites should not be SPAs and vice-versa. Personally I think that an SPA should be something that lives behind a login.