Like Wizful has said, there is, in fact, a limit to teaming, that being a maximum of about 5 players. Although it's not necessarily a rule (on KitPvP) in which players can be punished for, PvP staff members are more than willing to help you break up the group of teamers.
Yes, it's understood that teaming can get frustrating, especially when trying to do something like 1v1 another player. If you wish to 1v1 another player without interruption, nothing is stopping you from going to an isolated part of the map or even a different server if it comes to that. As said above, duel arenas should be released soon. Unfortunately, no one has an exact date as of yet.
If you are completely against teaming, we do have a Barebones server where teaming is a punishable offense.