I said nothing about sound quality. That doesn't matter. I don't care if the Mass sound better, or if I have a pair of £2000 speakers high end, of the same driver size.
It's about driver size.
And yes Bose comparison is valid. How big are the drivers in the Jewels? 3" What frequency response can 3" drivers reproduce? Not much.
Are you telling me the Mass 4" drivers have lower frequency response than the 4" in my Wharfedale Diamond 9.0?
And you can use the comparison for the Mass sub as well. It's a 10" driver, that's ok but if you expect earth shaking bass and output, you won't get it. You need to size up 12", etc, or go bigger cabinet, ie 13", with 100l ported cabinet native tune 20hz.
I think you may be completely numbers obsessed - that's okay.
I've owned, recommended and setup many AV systems over the years. I always used to be in the same boat as you - bigger is better. But it's not true, not always.
Going back to your original point, it's to do with physics. You can manipulate the perceived volume of a sound wave by changing its path from a speaker. Bose make use of this very concept, as do apple. It's called wave guide.
Subwoofers have used it for years, through ports.
An 8 Inch sub engineered correctly will produce incredibly deep, eye shaking bass. I know this, because I've tested it. It also means it can hit higher frequencies, because it's easier to move quickly.
Let's use Sonos as an example this time. Their Sonos Sub, which I happen to own, uses dual facing drivers, which I believe they say are 6 inches in size. The level of bass produced by the sub is immense. More than you would ever need in a 5.1 setup.
I've owned some of Mordant Short's stuff as well, and their subs are often 8 inches, or at least used to be when I recommended their stuff.
The monitor audio speakers, without a sub, won't produce deep sound. But as a combined system, it's great. So considering you haven't actually heard them, I'm more than happy to bet that OP would find they provide a full sound with deep and impactful bass.
As it happens, I did even advise looking into a 2.1 system as well, because as you say, having bigger drivers in the main speakers would offer a better frequency response.
But that doesn't mean they're better sounding.