Mostly folks who bought base model with small amounts of RAM I imagine.
While it’s workable, anything less than 24GB to me feels rather constrained. I definitely am not efficient though - leaving way too many browser tabs open I never actually get back to, running a few chrome profiles for work/side hustle/personal, etc.
I don’t think I’ve ever been CPU constrained for many years now. The few times I need to something that maxes out CPU just isn’t worth the upgrade vs taking a break to grab a cup of coffee.