A Nunu was raging at his team with "useless team" and "report x," so in post-game I explained that additional reports don't matter. He flat-out didn't believe me. I said it was confirmed by Rioters, and instead of saying "i'll google that (to prove you wrong)" or "link (that you must not have)," he proved his point by stating that his uncle works at Riot, and dropping a name. Right after I told him that asking for reports is considered harassment, he left the lobby.
It felt more futile than resisting the Borg with a phaser they've already adapted to.
I would recommend making little tips like "calling for reports is useless and bannable" a lot more visible. Perhaps the post-game stats page could have a section for inappropriate things a player was detected to have said? Maybe a pop-up notification like we get with Honor?
######I was going to say "more futile than resisting the Borg with a butter knife" but the Borg somehow can't adapt to physical attacks, so that wouldn't actually be as futile as I was going for.