[lmm]

I agree with you as far as C++ goes. I think the difference is that the things Scala adds respect the rest of the rules of the language.

If you introduce exceptions in C++, everyone working on any line of the codebase needs to understand exception-safety. If you introduce RAII you have to enforce it on every constructor, and since constructors can fail you have to introduce exceptions. If you introduce templates you have to use RAII for all your types in case they're used in a template.

In Scala if you use a higher-kinded type it works exactly as you'd expect (indeed I'd argue that the absence of higher-kinded types is equally confusing - why can't I use List as a type parameter in Kotlin?) - a method or type that uses HKT acts like any other method or type. If you have a function whose implementation uses a pattern match it might make it confusing to read that function, but to any caller from outside that function still conforms to its signature and still makes sense. If your colleague writes a Profunctor instance for one of their types and litters your code with ^>> calls that's probably annoying (and should probably fail code review), but ultimately it's just a plain old function call that you can click through to in your IDE and see what it's doing and whether it makes sense.