I mean, I've dropped in and out of the Ruby, Python, Javascript, Go, Clojure, Elixir etc communities and they all trying to be welcoming. It's kind of a given. It's rare to find the language community that isn't welcoming, and I think you'll find even that the most stubborn (lisp, Haskell) are very happy to have you and very happy to help new users.

You probably have an argument that they are doing something different and right, but how markedly different is it really?

I agree that most programming communities are friendly and open.

I can't help but notice that the same communities that have the reputation for being prickly are the ones that have the largest influx of people who come stomping in to the community, and one way or another try to turn the conversation to why everything the community is doing is wrong and stupid and how everything the community is doing needs to immediately be rewritten in accordance with their unambiguously correct opinions, even though they just joined the multi-year party ten minutes ago.

No, I do not have some particular community in mind that I'm coyly not specifying when I say that; it is a pattern I've observed across quite a few communities.