Considering that games can easily be determined at the loading screen and can be decided in literally the first minute from an invade, riot should let teams surrender at any time.
Also let the surrender vote pass at 3/2. This is a game which is far less important than congress passing laws which already allows the senate to break filibusters with just a 60% vote too. I don't see why a minority of players can hold everybody else hostage. If 3 players on your team think the game is completely lost with no chance of coming back, it is probably over, or at the very least very unenjoyable to play out a completely lost game with a small chance of an actual comeback. IF they are voting yes just for the heck of it, they are just trolling/griefing anyways.