It’s not “capping” as much as defining the x-axis of the normal distribution.
343 have set the definition of a mean of 900 and a left hand limit of 0. The curve should be symmetrical so the right limit should be 1800.
We are assuming the six deviations are each a standard deviation from the mean (that would make sense) and this seems to fit the % size of each group.
And this means 1800 would be the “ceiling”. Not many would get this far, and according to the standard deviations less than 0.15% of people should be above this.
My point was that the spread of MMR may be interfering with match-making (if it looks purely at a range of MMR).
The grind that is happening is distorting the curve.
Top players are going on huge winning streaks against lower ranked teams (this is all that the match-making can find on their local server) and grinding their MMR up and up a piece at a time.
From a rank distribution point of view it is a false economy. It’s no longer the good players playing each other to decide who is best - it’s a race to beat the most lower ranked teams.
The only way to fix it is to have a regular (eg. weekly) redistribution of MMR.
It would be easy for 343 to sort through the results retrospectively and use the games between closely ranked teams to create a guassian of skill. They can then reassign this curve 0-1800 or Bronze-Onyx or 1-50.
It doesn’t matter which, the important part is that everyone would be sorted into a meaningful order. The relative MMR between any two players would make sense. They could even allocate Champion status again (eg. to the top 0.1%).
As I mentioned it doesn’t matter how you label the x-axis; 0 to 1800, Bronze1 to Onxy6, or 1 to 50. As long 99.8% of the population fit into the curve then it will make sense.
It is weird how people were quite happy with just being a 50 (even in Halo 3 where it was equivalent to an MMR of 1300). Nobody spent hours trying to manipulate the system and grind themselves up to 50.1
343 should have continued the tiers into Onxy; 1 to 6, and left it at that. People could have earnt themselves Onxy-6 and be happy. But now, with 0-1800+ they have lost control of the curve.