Wtf is plat?

What the actual fuck is this elo? Like im climbing back to plat after quiting for almost an entire season... What the actual fuck happened riot? Like for the past week i have seen at least 2-3 trolls on one of the teams. Not like inting or anything, but just so bad that they do not belong there. Like they are legitamately retarded to the point where even challenger players would find it hard to keep a perfect winrate... let alone a 90%. You get these games where people just don't do anything, you get these games where people don't know how to play their roles. And believe it or not, these people have almost 1-2k games in plat 5-4. Anyone else notice this shit?

Add me @ Don't fucking delete my post riot games.