That, and it's really easy to tell the difference between the occasional genuine DC and a habitual pattern of Alt+f4ing the second you get downed. They wouldn't even have to work out which is which on the back end of everything, just have an ever-increasing timeout on requeues every subsequent time it happens. That way a genuine DC would just have something like a 30 second requeue cooldown, which isn't that bad at all, but when it happens the second time in a row it's now 2 minutes, then 5 minutes, then 10 minutes and so on and so forth. Ragequits would fucking disappear overnight.
Not to mention, if your internet is so shit that you're ruining the game for everyone else, you shouldn't be allowed to play either.