One thing that happens too frequently

So I try to be a team player and every so often someone gets filled into the adc role and begs to trade because they're "so bad" at adc. So when no one says anything I say I can adc IF YOU'RE TERRIBLE AT IT. I keep a reasonable score, I'm not freaking Gosu or whatever. Adc is my least practiced role. So then the guy spends the entirety of the game trash talking me for not playing adc the way he thinks it should be played even though he said he wasn't good at adc. I wasn't 7/0 but I also wasn't 0/7. I played fair and our team comp wasn't very adc friendly, as we had a yi and trynd on our team and they're not team player type champs. Our support was a blitz so if anything he pulled the assassins to me. I went back to defend our nexus from a superminion wave when the enemy team just got stopped from doing baron, and I saved both our towers. But then I got blamed because m team couldn't do baron. I thought that Nexus towers were more important than baron. Is this what the adc role is? Either my adc is a total asshole or the team is a total asshole to the adc. Out of the goodness of my heart I let a player play a role he felt comfortable at, telling him I was mediocre at the role. He ACCEPTED THOSE TERMS. And yet I get targeted for harassment anyway. Now sure, I let words slide off me yadda yadda. The point isn't that this player did this to me this one game. The point is it seems to happen a lot more than it should.