A reminder that surrendering is in the game for a reason
No matter how good you are, once you've played enough games your win percentage will never exceed 50% by much. Some games the odds are just so stacked against you that there really is no point in trying, where the only chance of victory is them throwing the game.
The Reds and the Boards, Summoner's code and such all preach about being nice, or at least considerate and respectful of your teammates. The game is more than raw mechanics and reflexes, its about perception of what you can't see meaning how the game is playing out. And sometimes, you have to perceive that the game is lost. When the enemy team is up double your kills, 5 towers, both dragons, and every single team fight they win with an ace losing only one, or no people. On top of (to me at least) what seems to be an upspike in afk's/people lagging really badly.
Yes, might be able to win. MIGHT. However, on the incredibly likely chance you do lose, all it does is make people more bitter and more on tilt that it took 40 minutes for the game to end because the enemy team wouldn't push.
This is where surrendering comes in. Surrendering allows you to end a game early when it is apparently that you have extremely low odds of victory. It helps put the game behind you by accepting that you lost, and ending the game of your own volition. This ultimately helps cure a little bit of tilt that may be going on, or just help you get over that one bad game.
But when you have "Blind Optimism", where people refuse to surrender on principle. They reflexively hit no. They keep preaching about "We got this". About how all we need to do is pick the one person on their team, when they constantly position well and have enough disengage to prevent dive. About they are throwing by not ending. No, they are enjoying the game at my expense, and so are you. When you won't accept.
When they refuse to end the game for no reason.
Surrendering is a feature added to this game for good reason. Yes, sometimes you should hit no because winning the next teamfight is a matter of how you go about it. But when all three lanes lost and the jungler had no presence, when you are scared to even leave your base, or hell, your fountain. Statically speaking, I'd rather boot up a new lobby and try again for a win by surrendering at 25-30 (ff at 20 is usually not how i roll unless people feed real hard) than play out a 50 minute stomp fest of them drinking beer and shooting the shit in team chat while the roll us over and over again.
Sometimes, it's best to move on.
TL;DR: Don't just blindly press no, regardless of your optimism. Consider the attitude others putting them on tilt that game, and just accept the fact its over and surrender.