New division below Platinum
I hear so many people say there is a huge difference between Platinum 5 players and Platinum 2-1 players; THIS IS THE TRUTH. This is why everyone speaks about Platinum 5-4 as the worst elo hell ever. There is actually a reason why those new promoting players get stuck for mounths in Platinum: They are actually REALLY far from the play level other Platinum players have and they just keep making their team lose games by doing important mistakes. Finally, alot of players get on-tilt because they get matched with them too much frequently; they are so not likely to play at their best. There is even a risk that they start trolling / leaving games / being toxic. This makes Platinum 5-4 not only the hardest divisions most Master and Challenger players had to pass trough, according to what they told me, but the division with most toxic players of the game.
To find a response to that problem (yeah, let's call that a problem), we said (as a joke) Riot should downgrade every single Platinum players to Gold, Gold players to Silver, Silver players to Bronze and finally perma-ban every single bronze players. Again, IT WAS A JOKE, but, in a way, we could put another division below bronze and it would be good, but people would just cry they lost their achievements. That could result into an overall negative experience. So the best we've found to do, is to create a Division between Gold and Platinum, say Ruby.
Ok, this would not ABSOLUTLY fix the problem INSTANTLY, because there is already so much players around low Platinum that do not deserve this MMR (or at least they cannot deal with MMR a little bit higher), but it would PREVENT new not deserved promotions unless the player makes several improvements along a given division, say Ruby. Over time, players which can't deal with high Platinum players' MMR will slowly be pulled back into that new Ruby division / will simply improuve themselves. I think this is a really good way to fix this problem. And ruby borders would be nice.