In the team you can VOTE and your vote is equal to all others. Imho you should respect your team vote and give it all till the vote is positive to surrender or your nexus is destroyed.
What's not fair at all is ppl giving up at minute 10, staying afk on fountain, or afk farming, int. feeding with no effort at all to improve.
Imho it's impossible to improve if you don't even try, if you go next on a hard game, if you only play "carried games"...
Long made short...Please, act HARDER on giving up behaviours in RANKED games please.