That would be TurboLinks. It's going strong, and has seen significant improvements over time. Especially when paired with something like Stimulus and/or Reflex and/or Hotwire, you can make some _very_ snappy feeling server-side rendered HTML. At this point, I won't even consider making SPAs for anything unless the product owner has an incredibly compelling reason.
If you're curious what the modern state of server-side HTML Rails can be from the user's perspective, head over to hey.com and sign up for their free trial.
If you're curious what the modern state of server-side HTML Rails can be from the user's perspective, head over to hey.com and sign up for their free trial.