C++ templates and metaprogramming is fundamentally incompatible with the idea of your code being treated in modules. The current solution chosen by compilers is to basically have a copy of your code for every dependency that wants to specialize something. For template heavy code, this is a combinatorial explosion.
I think that SFINAE and, to a lesser extent, concepts is fundamentally a bit odd when multiple translation units are involved, but otherwise I don’t see the problem. It’s regrettable that the question of whether a type meets the requirements to call some overload or to branch in a particular if constexpr expression, etc, can depend on what else is in scope.
In Haskell, you can't ever check that a type doesn't implement a type class.
In Golang, a type can only implement an interface if the implementation is defined in the same module as the type.
In C++, in typical C++ style, it's the wild west and the compiler doesn't put guard rails on, and does what you would expect it to do if you think about how the compiler works, which probably isn't what you want.
I don't know what Rust does.