I think reporting players is the worst function that has be designed to improve the game. I have seen a lot of time that player A asked other players to report player B because player B did not play well. I don't know what reason they report that player for since there is no such a choice that the player cannot play the game well. The idea to have the reporting thing is to improve the game environment by punish the players who have bad game behaviour. But the fact is that the reporting thing ruined the game. As far as I know, an account will be banned if the player was reported a lot. If a new player is reported by his teammates instead of getting advice about how to play, this player will not care that if the account got banned because the player will lose interest about this game and think that this game do not worth playing. If we lose our new players, this game will go to an end. Team communication is important in this game. Encourage the new players will make them be more interest about this game.
What I think is that we can provide some tutorial videos to teach the new players how to play well and suggest them to play some self practice games and watch some games (especially TI since it is free, and for TI I suggest we have a tutorial narrator who will also talk about some useful techniques during the game cast). One have to learn and practice if he/she want to play DotA 2 well.
And I suggest we add a new function which is called "blacklist". If you do not want to play with some players again, you simple put them into the blacklist, and you will not match with them anymore. And I think it is somehow impossible that someone shows on all the other players' "blacklist".