It's interesting that when they forked in 2011 they switched from a RoR app to an SPA (angularjs then angular) + REST api to be able to get better UI interactivity. Now it's 2024 and after we've had SSR and hydration, JS frameworks are moving to even tighter integration between client and server (for example React Server components).
Yes, we are moving away from the SPA approach. If you follow our latest feature developments you will see that we now try to adopt the HOTwire approach in combination with GitHub's Primer ViewComponents. And it is fun!