It seems some things are crystal clear to you because you are already used to them, but here you do not "see" how this will work, so you have your doubts. Fair enough.

To me it is crystal clear how this will work, and I much prefer this to generics in C++ and Rust or other similar languages.

But I am not saying it is wrong what C++ and Rust does. So if you prefer this, those languages are there ready to be used. I just think there should also be a good alternative for people who do not like how this works there.