It cannot affect TruckersMP because friendless players mostly play on crowded servers and they love to play. But SCS software is designed to do things like small convoys between friends. So TMP will not end.
My radio stops at 19. My first job when I enter the game is to turn off the radio because there is a lot of unnecessary talk and spam. I don't usually use the radio, I talk to my friends from 3rd party apps and I don't need the radio.