This would also mean: less players
Imagine a person telling a friend about TruckersMP and just think about what they would like to do. They would like to play together most likely and the friend now buys Euro Truck Simulator 2 for the first time, already has to drive a little bit for himself and after that, he still wouldn't be able to join his friend(s) in TruckersMP, because he has to drive a lot more to get more levels?
These requirements stop people from joining TruckersMP and the community would probably shrink as some people stop playing after some time anyway.
I do get your point, you don't really want those trollers in the game.. but that's not stopping those people - they will probably find a way to evade these requirements.