People take URF mode way too seriously

So I wanted to try out in URF (because spam allllll the abilites). I go into a game and lane against a Zed (who spams even harder). I lose lane and the fed Zed destroys us. Then my team rages at me for picking an underpowered champ in URF. Ok, understandable I guess, some people really want to win.

Since I got stomped, I wanted to try Jax again, this time spending most of my time in the jungle to avoid the op champs in lane. I end up being able to 1v1 the enemy who is 6/1 or something at this point. After this happens a second time, he opens the floodgates in /all chat.

"Oh, it's not surprising we're losing. The other team has autopress champs like Jax and Ziggs." Well, I guess I can understand where hes coming from. Jax is really, really spammy on URF.

A few more Teemo deaths later...

"You're so cool, autopressing on URF and playing a champ like Jax." (Or something to the tune of that) Our Malph finds Teemo's saltiness delicious and goads him on, prodding him in /all chat with caps. Teemo is thoroughly pissed and spends the next twenty minutes trying to prove how cheap I am for playing Jax and autopressing, and also fervently trying to convince us of his lack of frustration.

By the time the game ends, he has been exclusively on chat, spewing stuff about autopress and op and I'm not mad you're mad and etc. etc. etc.

In the post-game chat, he accuses me of exploiting autopress and sends some link about something called GameRef, which is apparently about anti-cheating software. I hadn't even known he was being serious about it, so I ask him if he really thinks I'm cheating, to which he replies:

"Who said cheating? You're the only one who said cheating. I can't believe you all thought I was mad. LOL"

How does one respond in this kind of situation? Why do people even take URf so seriously??