I mean, I don't find that working with IntelliJ makes it any "heavier" than other languages in terms of prototyping. I use PHP Storm for Laravel development and I never say to my self, "if only I wasn't using an IDE, maybe I could get this site put together faster". Quite the opposite, Intellij makes me super productive.

I think all of these frameworks - Laravel, Rails, Django, Next.js, Spring - require deep familiarity to get the best out of them.

> Honestly I struggle to see how they could've done it without making the compiler and build tool much faster

Well, Lightbend literally was the owner of Play, SBT, and Scalac. They were in a perfect position to make the build tool and compiler much faster. Or even if SBT can't be made much faster, ditch it and make integration with gradle and/or maven really great.