Troll supports will troll

Basically, i was just in a game went 11/3 as aatrox like i normally do and i had to go afk for a few minutes because my dad had just found out my dog had some kind of disease. So, before i went afk i told me team ''TURTLE GUYS, TURTLE'' because the kha'zix on their team was fed as fuck, and even i had trouble killing him even with my 6/0 lead i had against my opponent who was another Aatrox. So by the time i came back, i found we had lost all our inhibitors and were down to our nexus towers. I then later found out that it wasn't because my team sucked, it was because our janna support kept ulting their whole enemy team away when ever our cass ulted. And let me remind you, our team had a big lead since i did gank after i had taken out top. And this wasn't your typical janna ults by mistake, she did this everytime, even flashed in there to ult them away. So here's what im wondering, why do i get these types of people in matchmaking? I mean i gank the lanes that are struggling, keep my top from getting fed, but i still can't carry the team. Has this ever happened to any of you guys? Well, you getting the troll support.