4/5 on the other team should be equally dumb. Just think about it like a beginner/intermediate bot game.
In theory, yes. In practice, no.
Funnily enough, the only people with this mindset are currently in the same position as you, and fail to realize that mindset is to blame just as much as their teammates.
However, you're the only person you have control over. Instead using your team or the matchmaking system or whatever else as a scapegoat, try identifying the flaws in your own play. Once you carry yourself out, you'll look back and realize you were just as much at fault as anyone else on your team and feel good knowing just how much you have improved.
tsm are the homies and now i'm under tsm so now we like a gang of super good videogamers and homies