Both are true actually @Greboth.
CoD will always have a big pool of players, so it would be nice for them to experiment with:
Casual Core - CBMM
Casual Hardcore - CBMM
Competitive Core - SBMM
Competitive Hardcore - SBMM
On a game that still gets bought by the millions, splitting the pools like would get the desired effect. I don't want to be stomped all the time and would rather see how well I can do, but I also understand when we just wanna have a laugh and kick back in some random casual modes where games can be all over the place. Overwatch has it, Rainbow 6 has it, I don't see why they wouldn't do the same here.
P.S. Obviously SBMM in those modes above could have some element of connnection based checks so you aren't playing a random thats on a ridiculously opposite ping to everyone else perhaps.