Wasn't the wasp waist designs of some military jets from the 50's and 60's to do with area rule
That was the first purposful application of the concept.
Even the swept wing contributes to area rule, but as we all know the swept wing was introduced for all together other reasons. Another serendipitous occurence.
your points about area ruling are good, but remember the aircraft you referenced were designed to fly much faster than (subsonic) commercial aircraft
Although the aircraft may be subsonic there may very well be sonic, or near sonic, airflow somewhere on the airframe, typically seen on the upper surface of the wing as a line stretching out along the span. Wave drag becomes of importance at .7 to .8 Mach where supersonic flow somewhere on the airframe will induce wave drag. The aim of area ruling is to alliviate, or reduce, the possibility of supersonic flow being created.
Whitcomb began exploring applications of his area rule to subsonic commercial transports during the late 1950s. He quickly discovered that making relatively minor changes to the external shape could significantly reduce the drag these aircraft experience. Compared to the radical "waisted fuselage" shaping required for supersonic flight, subsonic aircraft could be made far more efficient simply by placing elongated pods along the wing trailing edge. Whitcomb referred to these pods as "antishock bodies" like those shown in the wind tunnel model pictured below. Also note the large bulge above the forward fuselage that Whitcomb found further improves transonic aerodynamics. This concept was later adopted for the Boeing 747.
