In the MOS, stalls need to be able to be recovered in straight and level flight, climbing, descending and turning.
The descending stall requirement seems a bit unnecessary. If the aircraft is descending wings level as on final approach, presumably one raises the nose to reduce speed and facilitate the stall and therefore you are not descending anymore.
Now try descending again with the intention of banking at the same time and it is likely to finish up in a steep spiral dive with ever increasing airspeed. Good way to exceed g limits and over stress the airframe.
OK I'll go along with a climbing turn stall and associated recovery action. But cannot see the point of a descending turning stall. Certainly not a requirement in jet transport simulators so why in a Cessna series singles or LSA?