Honestly, I do not see why this should be taken seriously.
Afterall, Minecraft is for all ages meaning younger children are allowed to play it.
Just because you might get annoyed by them doesnt mean they shouldn't be allowed to play.
However to help you out, if someone is indeed being annoying in for example chat you can try using /ignore playername.
And otherwise if it's just player team based the problem, try inviting/making some friends and play together. This way you less likely play with people that dont want to follow your plan/tactic.