It's not encouraged. And in comment section, I would definitely expect to see moderator action if it gets personal. Not sure how they would/could handle it for credit pages though. I have seen a couple groups fight each-other and even encourage readers to harass other groups via the credit page.
Well, this is a passionate community after all. Not often do you see this level of work being done for free by groups of volunteers. I just always hope they don't get discouraged by each other and simultaneously rage quite.