Try developing Slack or Discord with Rails and turbolinks. The point is, some apps are naturally SPAs. For those that aren't then it is unneeded complexity to make them SPAs. Also personally, I have had great experience with Vue in an SPA.

Yep, it's my go-to for any not huge web project. Plays well with any server-side tech you want, though I find Python (Flask, again with the right architecture, is a good experience) to be quite easy and enjoyable. The key is a sane and simple enough architecture from the start, which comes with experiences (aka making mistakes). But I personally go with Vue/Angular 1 consistently, trying to go more Vue now that Angular 2+ has IMO gone off the rails (heh).

Ember.js follows similar principals than Rails. Modern, matured, great ecosystem. You can move really fast with a Rails API and Ember.js frontend. Really, really fast.

Yes. I/we are using AngularJS to update some applications (apps, NOT sites) that manage state forms from initiation within private organizations with a workflow through the counties up to the state. There is quite a bit of interactive validation and input formatting / lookup support in a small number of very long forms, so it helps to have most of the interaction on the client side.

Also on the plus side, the back end requires less code now. IMHO, where Java is concerned, less of it is better. (There is still WAAAAAAAY too much of it, compared to equivalent Rails code)

Javascript might not be quite as good of a “Simula 67” as Java is, but it’s a much better Smalltalk or Scheme than Java is :-). (A comparison which probably doesn’t hold for JS vs Ruby)

Elm + Scala works for me. I'm using the same elm source with minor variations for both web & mobile (wrapped with cordova). So far, it's been working wonderfully.

That's an odd choice given Scala.js, any reason you're not all-in on Scala?

The elm architecture removes the need to make decisions when it comes to structuring the app. The tooling is first class. While I'm not sure, I think elm has a larger community.

We used Elm + Erlang and have been very happy