Well, a good example is that we literally had the golang generics conversation on HN yesterday. Forum goers are not machines; fatigue can easily set in. What can be perceived as hostility to those who desire debate can just as easily be people who are tired of the same "debate" over and over again.
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.
The FAQ merely states that generics remain an open issue. That doesn't replace a debate about it. On the contrary, it shows why a debate is necessary.
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!
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.
[1] http://golang.org/doc/faq#generics