It's also not unlike JSF in the Java world, which went out of fashion 10 or so years ago, and for good reason: relying on a framework to paper over the distinction between client and server side turned out to be much more complicated and fragile than a cleanly defined separation. I haven't seen any authors or users of these recently developed server-side-first frameworks discuss this prior art, but I'd be interested to see if they've come up with a way around what seemed like a fundamental problem in the approach.