I figure a surrender vote is just a straw poll. Best that it's anonymous, so no one can be attacked for how they vote. If it fails then you keep playing your hardest, maybe ask what people think they should do to win, but you keep playing.
It's really annoying when the same person spams surrender votes every time they can. That's the person who's just given up and isn't trying anymore.
But you need a 4-1 vote min to surrender, so clearly more than one person thinks the game is still winnable if the vote fails. Maybe instead of surrendering so much you should look at how the game could be won? I see more surrender votes at 20-25 minutes when most of the towers are still up and the game is pretty even than when the inhibs are down and super minions are pouring into base.