Why does matchmaking take so long?

Why, when it is finished, does the lobby collapse and send me back to the main menu?

Why, when it does not do the above, does the matchmaking go out of its way to put all high level players on one side?

Why, once we are in a game, is the connection so bad?

Why, once we are playing with bad connection, does the lobby spontaneously crash, sending me back to the main menu?

Why are you so useless?