I am curious why the door plug is not a plug door — that is, a design wherein the desired panel would be installed from the inside and sealed by the differentia

I am curious why the door plug is not a plug door — that is, a design wherein the desired panel would be installed from the inside and sealed by the differential pressure, like a cabin door. This part looks more similar to cargo door; those usually have to open outward for space, but what is the design constraint for this case?