(this is mainly for my iron/bronze friends, but also kind of a pointer for everyone)

Competitive games almost always last for 30-40 minutes. Don't think you can "squeeze in a quick match before you go". The amount of people who AFK just because they "gotta go to dinner :/" or "aw gotta go to work" or something like that is ridiculous. You know those things ahead of time and should have the forethought of "huh, instead of throwing the game for others, maybe I shouldn't queue up for a comp match and instead wait until I get home." Having to AFK for decent reasons, like your stove catching on fire or an important sudden event that you have to address immediately, is understandable. Having to AFK because you can't manage your time well? That's infuriating.

TLDR; if you want to play a quick match (or something that won't penalize everyone for your AFK), play unrated or deathmatch or something. Please save everyone the time and energy and don't queue up for comp.