I'm going to chip in here and take it to another level. In case anyone doubts your post here, I was on a couple of those channels and can attest that you speak the truth.
Now I'm not as seasoned as some Steemians, but I'm not a greenhorn anymore either.
What do you think my reaction was to see someone who holds some clout here on Steem not even get the courtesy of a hello?
If no one is willing to give you that courtesy, what chance does anyone else have of a warm welcome?
I wouldn't even make an appearance.
So take the newcomers that you mention aren't being welcomed, and add pretty much everybody else to that list as well.
If you want to know how to kill a community, I'd say that is step number one.
yip! in a nutshell.... SPOT ON! Sad but true @inalittlewhile