Why Do We Even Do Placements Every Season?

Has riot ever actually commented on this?

All it has really done is piss off the majority of players by knocking them down into the previous elo they had worked on to climb out of.

I've been playing now for 3yrs+ and while I am not the best player I understand the mechanics and most strategies but every season I am stuck playing with players who have never played ranked and those who troll/afk too much to ever climb. I am not a plat or above player than can shoulder a team of feeders and win, so instead I have to suffer until I can manage to get a couple consecutive games with competent players which seem to be in very short supply at the moment.

Most of my friends just simply aren't playing right now because in their words "there's too many idiots at the start of a season"