as long as laptop motherboards have to conform to custom shapes and thermal exhaust designs in order to be small and light there will always be a certain proprietary nature to them.

it's not like there's a standard for laptop motherboards similar to the 12"x9.6" ATX motherboard with ATX rear-IO-panel design we've been using for common midtower desktop PCs for the past 20 years.

it would be nice if somebody did standardize such a thing for a modular swappable laptop motherboard with all the i/o ports along the left side, the heatpipe and exhaust along the right side, or vice versa.

even something like a framework laptop has a totally bespoke custom size/shape/design to its cpu+gpu heatpipe and heatsink/blower fan assembly.

but I agree with you in principle.

I mean, it’s not like AT(X) started out as a standard either. It evolved out of a proprietary but reliable design.

Realistically that’s how a laptop standard will have evolve into being, if a consortium got together to try to make one out of thin air it would almost certainly be a disaster.

So at this point, imo, framework’s motherboard is the eigenstandard: either it will continue to exist long enough to attract efforts to build alternative hardware around (as the pi sort of has for tiny form factor sbcs), or it will fizzle out and we’ll be back to square one.

But may as well be optimistic and assume it’s the beginning of “atx for laptops” the same way the ibm pc/at was until proven otherwise. Challenges to that place need to provide more, not less, compelling reasons to believe in them imo.

They don't have to adhere to a strict formfactor like atx/matx (which weren't standard for quite some time, but regardless). The ability to change out parts like memory/disk/wifi, expand the I/O, and replace the mobo entirely (or even repair single failed components, or take to a shop that can) is the biggest thing for me as a user.

Have any laptops/mobile workstations ever used ATX motherboards?

No but big ass luggable computers have used desktop PC parts back in the day, Google "Dolch lunchbox computer". If you wanted the absolute most cpu power in something like a portable workstation that would be transported from job site to job site you could probably do something with an expensive 170x170mm mini itx format board and a 140W tdp cpu.

Even a microatx is just way too awkward a shape for a laptop really. You don’t want a square motherboard in a laptop, you want a (rough) rectangle so there’s room for a large battery cell.

Isn’t that what a raspberry pi is ?

My son and I just assembled a devterm that is exactly what you describe … would be easy to architect other form factors around it …