No. Both type erasure and monomorphization have always been legitimate ways to compile generic code. IIRC, the issue with Java is that type erasure is sometimes a leaky abstraction.
What exactly do you mean by "leaky" here? Can you give an example?
My main issue with non-erased generics is that they actually break reasoning wrt. parametric polymorphism as soon as you allow for pattern matching or even just .isInstanceOf on type parameters. Suddenly a function which takes a List<A> can do entirely different things depending on what A is... and that takes away a powerful reasoning tool.
It’s leaky due to reflection, but type erasure is not a problem in itself. .NET did away with type erasure, but it had a cost in terms of language ecosystem of the platform - not erasing List<A> into List will bake the variance of List into the runtime, and thus other languages have to use the same model.
