Its even better than that, forcing quick play on everyone could potentally ruin ranked for the ranked players that so desperatly want it implemented.
Due to the sheer mass of people that do not want to play ranked but get forced match to ranked players it could screw up the stats, bringing players on top that are mediocre at best but really play a lot of games and gain points for their elo most of the time, simply by selecting ranked instead of quick play.
In Wargame if you were searching for ranked you get only other ranked matches.
Now its like, top tier player starts searching for ranked at 20:17 - no other player found that want to play ranked - he gets matched with quick play.
Mediocre player starts searching for ranked at 20:18 - the other good guy got already matched away because of quick play. Mediocre player gets a noob from quick play and levels up his elo rank. It gets even better, if the top player has a shitty internet provider and gets a disconnect counting as a loss in every 1/10 game.
If you assume that a majority of top ranked or ranked players in general is in specific timezones, you could level up easily the elo board in quick play without facing them ever if you are in a totally different timezone, since the overall playerbase gets so watered down.
Edit: Its like two gladiators that are used to arena fighting are now put in a massive army fight. Chances are high they won't find each other before they butcher their way through like 1000 other guys first