Implicit interfaces make generics a lot less trivial to implement. They also don't want to simply add an existing approach with bad trade-offs (see C++ template

Implicit interfaces make generics a lot less trivial to implement. They also don't want to simply add an existing approach with bad trade-offs (see C++ templates). Likewise, adding a runtime based multi-dispatch based generic system is not much better than what we already have. Lot's of languages have generics, but they have trade-offs, so they aren't free, even if they can implement them using existing generics implementations. Picking what they're willing to sacrifice can be hard, even if it's something like slower compile times. Anything backwards compatible has to be in Go 2 or later, because generics are hard to make backwards compatible, we'll have to wait.