What is so hard about that?
You just create a bunch of filters and run the MM through them. If no matches, you begin easing up the constraints of the filters or removing some of them (the server can do all that trial-and-error-readjusting in nano-seconds). It is only a matter of creating and combining filters really - including business-ones that will affect amongst other sales (and create an unbearable gaming experience over time).
I am a game programmer, although not specialized in MMs. But as a long-time player across multiple SR levels (from low Gold to low Diamond, even a brief stint in Silver when the MM was particularly nasty), I can tell you for certain, that something is wrong. As a high-Plat player with forays into Diamond, it feels completely off, if I can’t reliably win matches in low Gold.
Can you tell me who you are? You claim all this MM programming skill. For who? Are you a Blizzard employee out defending this crap?
Let the GM play 2-4 games in Bronze, and you will see him matched against one or more smurfs and his teammates dump in quality, until he is evened out. That will be repeated again and again, all the way up. Sure, he will climb over time, especially with that extreme a skill gap, but it will be a long and hard journey. That is how Blizzard’s MM creates “even matches”.