But if the warning occurs in private it will benefit just one person. If the warning is public it will make some others who were thinking off trying the same thing, not do it.

True but for that could have an automatic response like when they post that they are on maybe put up message stating, "Warning! Please follow chat rules, breaking them will lead to you being silenced, possibly ignored by other players, and banishment from game with extreme situations." chat rules being a link to them of course idk just a lot of the chat is mostly about the rule breaking and ppl telling others the rules which ends in constant arguements and as it is atm a lot of it is being done multiple times even with being told this would stop that much more. This is my opinion. Anything to clear some of the chat garbage would help but right now seems to be ineffective. Also, like many repeat over and over when starting the game you agree to the rules so that really is first warning.