Body-mounted couplers?

[Sumpter250]

In the larger scales, truck mounted couplers allow rolling stock to handle tight curves better than body mount. So, in larger scales you ( almost ) always see them only on toy train set cars, or on very long cars ( keeps the couplers "centered" between the rails better ).
Truck mounted couplers also have a tendency to cause derailments when "pushing", as in backing through a curve or turnout.
In these moves the forces are on the the trucks, and limit their ability to adjust to the changes of direction, which can cause deraiments.
Even on the long cars, like my METRA passenger cars, I prefer body mount couplers. The Walthers "coupler swing adapters", like those used on their autoracks, help address the coupler centering problem, while being body mounted.
Larger scales have been "body mounts" for a long time, while N and Z scale haven't been here quite as long.

" Is this merely an N-scale issue of some sort, or is it wider spread? " it's not as prevalent in the larger scales, so, not quite so much an issue, but it is there. Lionel O scale, to the best of my knowledge, still uses truck mounted couplers.