I would like to see your reference source that posit the view that the AMRAAM choice was a F-16 compatibility restricted determinant. The AMRAAM was a natural development from the deficiencies associated with the Sparrow primarily by the lack of an active terminal homing. While the Phoenix has similar capability, it was not viable as it was six times the cost of the Sparrow. When it came to the development of the AMRAAM, the intend was to ensure a broad application across all the major platforms including with the F-16 unlike that with the SparrowAMRAAM size/capability was determined by one single platform, the F-16. Any larger and the plane would struggle to be 100% capable of employing it as its main weapon. On the other hand, this way USAF a2a combat capability managed to get such an incredible boost in the early 1990s, one which, for example, the sparrow-sized missile would struggle to provide.