I've been the best player in games where we've lost, sure. Doesn't mean my team was intentionally feeding. And part of why Riot is so damn slow in catching feeders is because their staff is bogged down with folks rage-reporting people simply for having poor KDAs.
I saw one intentional feeder, on the other team, across my ten placements. Then another guy on my team who got tilted and sold all his items a solid 8 minutes before the end of the game. So, two feeders, out of ten games. Poor odds, to be sure, but your insistence that it happens in literally every game you play makes it hard to take you seriously.