tl;dr : check your teammates WR & champ pool, use at least your first dodge everyday, use your extremely valuable ban better than that.
Actually what you should be doing is taking 10 seconds before the ban phase each time you get into champ select to check your teammates profiles on op.gg and look at their winrates on X champion, their champions pool and so on, are you doing that every time you queue for ranked ?
As it is i don't really get your thread, you're complaining about something you should be able to avoid with a little effort and 10 seconds, if you were doing all i said in this reply and you were using your dodges effectively you just wouldn't have to worry about those situations. OP.GG is a really useful resource to know about your teammates before the game actually starts, and to know more about the enemy team once it started, you'll have access to their WR/pool/exact rune pages used, rank and such.
If you spot a bad Yassuo player yeah feel free to ban it, but sometimes it's much more effective to ban an actual meta champion, or something that would hard counter you..
Of course if the dude doesn't declare Yassuo, and then pick him, since you're able to notice that he either has a 25% WR with Yassuo, or even that he never played it in ranked, then I'd dodge and loose those 3LP, even if i loose 10LP it can be worth depending on teamcomps, dodging effectively is actually an easy way to gain a lot of elo you should at least use your first one everyday. [see actual numbers, page 4/5/6]
But yeah i wouldn't just ban Yassuo every time, i'd rather have a look at my teammates op.gg before doing so because a ban is extremely valuable so it isn't worth at all to instaban yassuo, i mean depending on the situation you'd better ban something meta or a counter.
