It feels like this much of the time, doesn't it? However, clearly more people are using Quick Play to practice heroes they aren't comfortable with and might never have played before. In my perfect world Blizzard would have an algorithm that looked at the amount of time you had spent playing any given character + whatever else they use and adjust your MMR accordingly.
If you were fairly new but wanted to practice against other people then you'd be put up against other "new" players for a little while until you had some hours under your belt.
How is an algorithm going to predict what hero players decide to choose after the matchmaking when they are also free to change heroes in the match as often as they want?