If ANYONE, regardless of level, needs to DC from a game to protect their average at the cost to the other players of the game and experience, that person needs to not play. If you can't afford to post what you shoot, don't shoot. Go play practice or something where it doesn't count.
In my opinion, any game should have to option to finish or to post a score that is an average of their per hole score at that time. The option to quit a ranked game without any effect shouldn't be there, in my opinion. It would also make the cut line for the Open a lot higher, as players couldn't restart over and over with impunity until they got the start they liked. And if not, I would posit that definitely any multi-player should have only these options. If you are in a multi-player, and are +2 after 6, you have the option to go in and finish, or to take a final score of +3. Or even let them extend the current score to the end... if you are even after 6 when you DC, you have the option to go in and finish or take an even score for the full 9 (or 18). You don't have the option to act as if the round didn't exist. Bad enough that, if you have 10 posted scores below that one, that one will have no effect anyway.