as I said... it's a suggestion... starting from the end, but I guess catched more attention and curiosity this way... or not!

Now, screenshot related: player got stations fixed after I told him to and explained why was not fair to other players the actual provision/coverage of his stations.
Teckers got the point (
wiki.openttd.org/Game_mechanics#Cargo_delivery_to_stations
) and it's quite common sense but, as player mentioned... it's not on the rules (vaguely on the official OpenTTD multiplayer rules, like it is implicit the 1 way train trick). And most of online servers mention this situation specifically because few players knows the game mechanics and have no ideia that cargo is only supplied to the 2 best rated stations. Meanwhile I didn't wanted to send him to n-ice detailed rules link or his brain would be even more messed up, due some differences on them

I think Ivanoz was already predicting what would be my suggestion. ^^
Could be, for example: "Competition is encouraged, but limited! You don't own cities but you CAN claim a factory, people can compete with you for any resources in a city BUT may NOT
compete with yourself or steal goods a factory produces with supplies from a competitor!"