Generics have been discussed to death regarding Go, and there is a long and complex history of the choices and realities in Go. So it is understandable that people can get a little irritated when someone stumbles in and declares that maybe Go should add generics, usually then decorating their claims with lots of exaggerated hysterics (most recently that Go is an "embarrassment" because it lacks generics. Quite the accolades for the people who work long and hard on it).
The most popular response to any language debate seems to be "it's not a problem in practice", implying all critics just "stumble in" and don't know what they're talking about.
They have debated this many times over in the past.
What they don't do is repeating that debate every week. It would take a lot of their time and is largely pointless (in the sense that person that starts the debate with 'go sucks because it has no generics' will not be convinced that it was the right (or at least practical) decision to make regardless of how cogent your arguments are).
That said, that's when a community should write up an faq[1] and then simply point to it in a polite way that avoids engaging in the same conversation again while still being welcoming to people thinking of joining that community. If people aren't doing that, it's somewhat understandable, but long term the acrimony can be poisonous.
I fully understand that the Go team and long time forum dwellers are not inclined to discuss the same generics proposals over and over again. So don't!
New ideas should be welcome though.