I think Elixir is a super interesting case given how insanely fast it is. If your request to fetch new data and patch the DOM takes 5ms, who cares if it's slower than React? It's plenty fast for a ton of use cases and lowers complexity.
And then, if you do need the super slick interactive element, you bust out React and code up a nice little inline thing that writes it's value to a hidden input field that you can send along with a the submission of a normal form.
Webdev swung heavy to building entirely frontend solutions and I think the past year or so has been the potential beginning of the pendulum swinging back as teams are now feeling the pains of maintaining these huge frontend applications, on top of already needing to maintain the complexity of their backend.
Time will tell!