I disagree.

Yes, any approach to parametric polymorphism is going to make some tradeoffs, but the benefits of C++-like generics which you've enumerated (templates perform as fast as hand-instantiated types and the ability to have complex constraints) do not require you to simultaneously have the drawbacks which the C++-like generics have.

For example, ML-style parametric polymorphism has shown us that it is possible to mostly have our cake and eat it too for 90% of cases where you actually need to use generics; unfortunately only very recently (e.g. with Rust, even if its flavour of generics is still limited compared to what you can find in functional languages) ML-style polymorphism has actually appeared in a more mainstream language.