I find rust and scala quite similar on learning curves. You have to reach a certain level before you can work with the language and library ecosystem.

The benefits proposed by proponents of both languages are there but after the mean of the bell curve.

Also a beginner is asked to work with external interfaces and libraries because the language and its standard library is defined to be minimal in certain ways. The answers to which are supposed to come later. So a lot to take it on the first step itself.

Both languages are still working on some answers and kept options open. So "why" of that is also complicated.