What you clearly missed here is the word CAN. He made a factual statement which you failed in your attempt to counter due to assumption. At no point did he say effort and motivation will ALWAYS.
Hope that helps.
Stating that unknown players have just as much skill / potential as known players is in no way equal to someone saying “they could be the best if they tried” This is simply more assumption on your part that you were attempting to project onto others statement. You cant manufacture context and then say someone’s statement is wrong that that context you created.
This sounds like an attempt to taunt or call people out. Its unlikely a skilled player would be triggered by petty taunts as they are less likely to be that insecure.