Do you speak for most sites?
I didn't think so. Maybe just speak for yourself. I was speaking of what I know concerning the forums I am a member of. None of those have had a problem with discussing those other sites, or when I asked problem members to consider leaving and joining one of them. We've asked people to consider leaving our site when they were troublesome, or unhappy, or felt they had been treated unfairly. This you know.... being one of them.
We encouraged them to seek different forums that might be more to their liking- where they might fit in better, be happier, and otherwise find fellowship such as:
TOL-- theologyonline.com
CARM Forum-
CARM Forums
Theology Forums-
Theology Forums
And of course-- here at Talk Jesus.
I'm open to being corrected (are you?) -but I can tell you that Chad-- the Admin here has been very kind and helpful to me and has assisted me with Xenforo (the software platform) upgrades for White Horse Forums when I asked him what he had imported here. He very graciously told me what he bought and where he found it. Kind of Christian-like.