I too have seen the Boeing progression drawings; I particularly recall the fuselage cross-section differences. The -80, C-135, and 707/720 were all unique in response to differing market desires. The 727 IIRC was same as the 707, but the 737 had a smaller lower (cargo) lobe.
Further, early on the 707 was available in different cabin lengths, to the extent even of a special model (707-138) for QANTAS long thin routes.
The point that was made in that presentation was that Boeing was responsive to market forces, whereas competitors - not so much.