I just don't understand this..

I went into a ranked game and got my chosen lane (mid). I flagged Zed but unfortunately the enemy team picked him before me so I went to my second pick (Fizz) but he was banned. Third pick Yasuo? Banned. My only option was Katarina who I rarely play and am not good with but I knew this and so I asked my teammates if I could maybe switch because the only champion I had left was Katarina who I could not play. They weren't bothered and said it was ok. I specifically remember one of them saying "You main Zed and so you should win because you know him better." I tried again for switch but this time none of them replied and so I had to lock Kat (the timer was at less than 10 seconds).

I go into game, not knowing what I'm doing and just as I thought, lost lane. Darius immediately starts flaming me, "You can't even play Katarina, never play her again. Why'd you even pick her." I was trying my best, I didn't recklessly engage, played safe, and didn't try to cs because he was zoning me but even after all that Zed was 6/0. It's a little after mid-game and my tower is gone. Sejuani (Jungler) finally decides to come but at this point, Zed is too strong. I was pretty sure he could 2 v 1 us and so I ask her "Why come now? It's too late. I'd rather you gank another lane where you can actually do something, mid is lost." Darius pipes up, "Stop crying, you suck. What are you whining about." Sejuani then says in [All] to report me for flaming. Doesn't mention the Darius who was picking on me all game. I wasn't flaming, all I meant was that there was nothing she could do.

I honestly don't understand people like this. Whenever this happens I always warn them that I can't play mid because (reason) and that if anyone is offering to switch I'd take it. Sometimes someone does offer a switch but the times they don't they either encourage me or ignore me but it doesn't matter because end result is always the same. I get flamed and reported as trolling even after I told them I can't play the role.

Because I run into this problem so often, I tried to broaden my champion pool and who I can play decently. I've bought Ahri, Veigar, Annie, Ryze, Brand, and even Galio for this purpose but unfortunately I'm not good enough with them to go against Zed. I am utter garbage at all of them. I can sort of play Galio but whenever I play Zed against him I win and so I didn't pick him.

I don't know what else to do, I bought more mid lane picks, warned my team of why I shouldn't play my role, asked for a switch, was denied this and ultimately flamed at and reported. I'm starting to dislike League because most players are so toxic or so focused on themselves, they don't care about other's situation until it starts to affect them.