TLDR: in most cases where it seems like people are teaming they likely are not, they either didn't see/hear it or are unsure of who killed or why. And if admins cracked down on every instance that could be considered teaming it would fucking suck
keep a cool head and realize that not everybody sees whats happening through the same point of view. During instances where disruptive and repeating teaming actually happens use !calladmin or start recording to make a player complaint.
surprisingly enough, abusive teaming also often coincides with the other rule RIGHT NEXT TO IT
ghosting is as damning as it gets for evidence so dont be afraid to start recording or to call an admin if you catch it once or twice