It seems like if you are developing solely to meet "SEO friendly" criteria, you aren't exploring many alternative solutions.
Does all this framework tooling exist to just avoid inspecting a user agent and serving from a different upstream?
Having to maintain a large set of template files, with a dependency on a separate language or framework seems contrary to your premise that Vue is specifically better because it uses "HTML templates by default"
Never said I was. In fact that's just another nice benefit of traditional server-side frameworks rather than something you have to worry about implementing all over again.
Blazor specifically is the first non-JS component-based UI framework for the web with multiple modes that bridges backend and frontend as a single service without any impedance mismatch. It's an entirely new way to approach web UIs and interactivity without all the plumbing and frontend-to-backend-for-the-frontend-to-the-backend nonsense. Livewire is not quite as polished but shows how far you can go with tight integration on the JS side.
It seems like if you are developing solely to meet "SEO friendly" criteria, you aren't exploring many alternative solutions.
Does all this framework tooling exist to just avoid inspecting a user agent and serving from a different upstream?
Having to maintain a large set of template files, with a dependency on a separate language or framework seems contrary to your premise that Vue is specifically better because it uses "HTML templates by default"