Surrender Votes

Why does it take a 4/5 vote to surrender in a game. I have played so many games now where my "allies" have fed like idiots - though I'm never toxic about it - but then they adamantly refuse to surrender even though the enemy team ends up with fed Zeds and Brands and such. Quite often 3 members of the team hit yes - which is, btw, a majority - 60% - over half - but then the other 2 feeders won't surrender so I have to endure another 20 minutes of a horrible game where we just die repeatedly to fed enemies. I understand the philosophy of - "there is always a way to turn a game around" - but most of the time you can't actually turn it around and it just gets worse. It's just not fun to play a lost match. So please, tell me why it takes 4 out of 5 people to surrender and not 3.