Most people who are quitting right now are players "who started playing back in season 1". Now obviously people in Diamond and higher have something to be frustrated about, but most of us are not in Diamond or higher. I've never been matched with a 4 man before (probably because I'm a gold scrub) and I'm honestly fine with Dynamic queue. I'm still quitting, however. Not because of Dynamic Queue, not because of a single balance change...
It's because I'm bored with League.
Eventually, playing a game almost religiously every single day will get stale. There won't be any more fun builds to try out, kill lanes to play with your friends, weird team comps, etc. Everyone will eventually get sick of it and move on to some spicy new game, like Overwatch or something. You're not quitting because of Dynamic Queue. You're quitting because you're bored and LoL isn't fun anymore, or at least I am.
Just my 2 cents.