I think it's a part of modern web developer culture. Where I work I started on a project which was already 3-4 months down the road and they were fully dedicate

I think it's a part of modern web developer culture. Where I work I started on a project which was already 3-4 months down the road and they were fully dedicated to react frontend and Koa on the backend. The whole stack was based on a react boilerplate the company built, as far as I can tell the idea of doing something other than JS on the server was never tabled. Likewise, the idea of rendering HTML on the server was never brought up. Everything is pure client side JS SPA even in places where it might make sense to just render things on the server or load a separate page.