I'm fairly certain you're displaying a nearly sociopathically low level of empathy here
As for "constructive criticism" going towards winning... it's almost always better to have team cohesion than to berate somebody for their past mistakes.
Look at it this way: if you're a positive presence on your team, they'll at least feel better and possibly perform better in the future. Conversely, if you're a negative presence, constantly nitpicking on mistakes that can't be rescinded, your team will just feel worse and worse and their performance will reflect that. Also, let's not forget that winning isn't the be-all-end-all. This is a video game, and a vast majority of people play video games to have fun. A HUGE amount of League's playerbase isn't even that competitive, both in the mental sense and in the skill-level sense. Gold is within the top 20th percentile of players. Think about that. Diamond is within the top 1st percentile. This is a game with tens, if not hundreds of millions of players, and over 50% of them don't even play ranked. 50% of those players who do play ranked are Silver or below.
Let people have fun. It's possible to have a good time even if you're performing poorly--a possibility that almost certainly gets taken away when somebody starts screaming at you for something you did wrong. Can they mute you? Sure. Would the damage be undone? Absolutely not. Does the damage even help you win? Most likely not. There is literally no point in being negative. Ever. The only thing it accomplishes is venting a small amount of frustration while building up an exponentially greater amount. You're just validating your anger and breeding more of it. I understand that the veil of anonymity makes it a bit easier to be unkind to your teammates, but they are your teammates at the end of the day. Treat them poorly, and they won't do you any favours. Cheers mate.