[{quoted}](name=My Flare Lady,realm=EUNE,application-id=3ErqAdtq,discussion-id=1IIEQ7cl,comment-id=,timestamp=2016-04-01T17:47:32.916+0000)
Because somebody can select Fill and just say "I go x" in Champ Select, forcing everyone else to play around them or troll. I've had jungle taken from me twice that way. First time I let it slide and they failed miserably (I might've failed as well, I'm not a perfect jungler, but I picked jungle, I should be allowed to try, not have it taken by a troll). Second time, I just picked Singed support.
Just remove the Fill option, it might encourage some people to pick their main roles.
The problem here is not that DQ has a fill option, its that the player in question is a troll. Report him, move on to another game. If you queue in DQ, you are supposed to play the role you are assigned, regardless of whether you filled or not. Clicking Fill doesn't mean you are allowed to do anything, it means you are willing to do anything, therefore the system can assign you.
If someone is doing that, just bear with it, a troll is a troll, and report them at the end of game. No matter what riot does to the queuing system, trolls still gonna be trolls. Its just to the community to slowly weed these individuals out via reports/bans.