What does represent the skill in Dota 2? Now you have the answer. The more you know the game, the faster you are going to finish your games. The better the player is, the more he knows about the importance of key objectives of the game.
Unimpactful kills, unnecessary fights, lack of movement around the map, all of these results in games being longer than they should.
One of the simplest ways to start playing around objectives is to use GOSU Voice Assistant. Real time help is going to tell you when you are supposed to pressure towers or do other activities.