Current rankings and placement games

Hey, guys.

So, I know this flex stuff isn't that big of a deal and that it'll only have a small impact on next season's rank, but I still find this annoying. I was Plat V last season. Barely made it out of the worst Elo hell that is Silver and Gold. Was pretty happy with myself, although I still think I'm better than most Plat players, but who can deal with all the trolls and AFK-ers. Anywho, I played my 10 placement games, got 2 afkers and one feeder, so I ended up winning 7 out of 10. Not too bad, since I got put in Gold III, which I thought was pretty fair, considering the hard work (ironic) I put into getting to Plat V. Suddenly, Riot releases another note, saying I need to play one more game to be placed again. I say fine, let's do this, how much harm can it do. I play Bard support, which is my main champ, but I, of course, get a 4/20 Vayne who's playing on a keyboard with no R key. Or Q. Or E. Luckily, W is passive. I was bummed, almost won it, but figured it wouldn't impact much. Little did I know, I'd be placed in Silver IV after the game.

Now, my question is - why, Riot? Why? Has this happened to anyone else? If so, which computer did you smash? Thanks in advance!