The logic behind the built-in airstairs on the DC-9, 727, 737 classic was that many of the airports that these planes would be flying into, in the 1960's, simply didn't have the facilities to handle loading and off-loading passengers, not jet ways. And it is cheaper to have the airstaris on the plane than to drive the stair truck up. Of course nowadays you'd be hard pressed to find a commerical airport that didn't have some minimal ability to handle full-sized jets.
Stop drop and roll will not save you in hell. --- seen on a church marque in rural Virginia