Why? Seems like most in the South knowledge they have great skills without making grandiose claims about who best fortress rooms. It might be a case of "grass is greener" syndrome, but one side definitely appears to have a more severe strain of it.
That's always been the meta. For 10+ years, meld fortresses have been the meta, as far back as original room choke that was actually overpowered in conjunction with melds and other roomwide passives. Forever and always this game has revolved around …
I'm curious what the proc chance is. The few times I've made a point to pay attention to it, it seemed like I got bounced out of the room consistently enough to disrupt me. I don't think it's that low, but my evidence is anecdotal.