Seriously, someone answer me this. Is it just the typical "run down mid" thing? Because after hunders of games, I can say that many games are lost because of other INTENTIONAL mistakes and they can happen throughout the entire course of the game, from champ select even.
-Champ selection. You see the enemy picking X champion and you get to counterpick it. Instead, you pick something that is very weak against X, and at the same time you are picking summoner spells that won't aid you vs X. For example, picking Velkoz vs Zed, and I can't tell how hard the lane is for Velkoz after level 6, but you have to understand that picking Teleport and Flash instead of having an Exhaust isn't the right way to go. Velkoz eventually goes 0/3 getting solo all-ined by Zed after level 6. That's an intentional mistake.
-Keep trying to fight someone, even when you're way weaker than them and dying for it. You go 0/2 top lane (with or without jungle assistance), and you keep fighting the enemy, just to die again. Sure, you wanna kill the enemy, but you can't and you just end up feeding the enemy.
-Optimizing (runes, masteries, items etc). I can't stretch this enough. There are certain R/M/I that work really well on champions and / or role. Mainly, I will talk about support items. Locket is an extremely strong item, same as Redemption. Having at least 1 of each in your team is crucial, if not necessary, to win CLOSE fights, or fights that you are behind. Obviously, these supportive items are mostly suited to be built by the support on each team. Failing to build those items can result in lost teamfights - games (I had 3 of them recently, close fights, decided by the enemy having Redemption and Locket and us not doing so). After being asked to build those items to help the team, our Blitz support instead built Frozen Heart and Adaptive Helm (whose passive was useless vs the enemy) and then proceeded to get an Iceborn Gauntlet. Same can be said about many things, for example not getting Windspeakers on Janna (DFT Janna wtf).
So yeah, I really need to know to what extent the above things should be punishable. Everyone makes mechanical mistakes, bad pathing, maybe not good csing etc, but the things said above are pretty much easy to identify or at least people can ask the team what's needed, or even do what the team says, since they obviously have no idea. I'm not saying that games are lost solely because the support didn't get a Locket, but optimizing itemization for me is crucial in a lot of stages, if not all. To me, this should ne punishable, because, if it's not, then I can go build full AP Caitlyn, not die and just shoot autoattacks and try to farm. Sure, I didn't die, I didn't feed, but I was also useless for my team and that should be punishable.