I mean, SBMM exists for a reason. I’m pretty old, and SBMM used to be non existent in every game that I played. But, they added it to games for a reason.
It reminds me of that blizzard saying…something like, “you think you know what you want, but you don’t.”
I agree with you (and with others sharing similar takes in this thread).
But I think this is worth keeping an eye on. I mean, this isn’t just some random shooter experimenting with open MM — it’s CoD.
If it fails, then yeah, SBMM remains the king of matchmaking (with EOMM trying to steal the crown or at least sit on the king’s lap 
).
But if it succeeds… well, then the king is naked. And it’s very likely that other games, even from different genres, will start testing the waters of open matchmaking.