Riot has continually said the different queues are for different things, ranked is if you want to play competitively, draft is to practice for ranked in a similar environment with less pressure, blind is for pure having fun (people are much more relaxed about troll picks there ^^) and teambuilder is for playing exactly the role you want, when you want to.
There is no "main queue". Anyways, while people might get pulled out of ranked at the start, they probably won't stay out of it for more than 2 or 3 games.
Just to point this out, but a 100 games is still 33 hours if people always surrender at 20 minutes (which we both know rarely happens). Maybe some people will be willing to play that long just for an Icon, but I doubt many people will. Rather people who already are playing teambuilder will get it.
P.S. Whoevers downvoting him, knock it off, he's entitled to his views....