Like everyone else you might end up in a bad match making with toxical people and because of that you would consider dodging the game to prevent a bad time and extra LP loses, however this is not possible in your promos. Doding a game will be counted as a lose and you would have to start to gain 100 LP again. I'm currently stuck in Platinum while i was Diamond 3 in Season 5 purely because of the lack of communication in game.
Instead of counting it as a loss, why not set it up that you can freely dodge 1 game in your promos? This would help and benefit for everyone that has problems with their Promos, and it could be very frustrating. (I was stuck in platinum 5 for 300 games/ 11 promos because of the negativity ingame.)