why we need to accept the result of the others AFK?

Some of guys afk in the game while after 3 minutes. No matter there is the proper reason or not, other teammates need to accept the result of that, perhaps can win but most of this situation are lost the game. I think this is really unacceptable and the system of this is totally wrong, especially in the rank. Why not learn the dota, when the other leave the game, the others could free to leave, both allies or enemy. What do you guys think?