In my experience spas have a much better ux. Have you guys used Jira before? It's actively painful and there even is some local interactivity. But whenever you need a page wide rerender it makes me twitch. Same thing with aws when navigating between accounts/products.

Also having a spa doesn't mean you need to have separate frontend and backend engineers.

But it does allow various value streams to leverage each other's APIs in their own front ends.