Well, when you look at the M1 lineup, hasn't it been:
- M1 - 8-16 gigs
- M1 Pro - 16-32
- M1 Max - 32-64
- M1 Ultra - 64-128
So... since we know that lots of components get doubled between each chip, I would guess there's doubling on the memory controller side going on as well.
In Windowsland, for many years, the bigger-screened laptops were LOWER end than the smaller-screened laptops. You could find lots of low-end 17" laptops and very few comparably low-end 13" laptops.
Apple has, of course, followed the opposite practice since... probably the move to Intel? And I'm sure they've had some success (and big profits) selling 15.4-16" MBPs to people whose needs would have been met quite nicely by an MBA except they wanted a bigger screen.
The thing is - is this the result of detailed market research showing that no one wanted a 15" with the internals of the 13" models for $200 more? Or did their market research tell them that people who wanted a bigger screen were willing to pay substantially more... so... let's sell them a higher-end laptop than they need and pocket the profits?
And I would think the same principle applies, if not more so, in desktops - with laptops there is a benefit to a smaller laptop, but other than to save money, would anyone rather have a 21.5" iMac over a 27"?