Originally posted by reh321 That is a rather cynical view.
Before EOS-R, the last FF mount change by Canon was thirty years ago.
If the older mounts are compatible, it makes no difference REH. Leica M-mounts cameras go back 50 years and the same mount is still used, though similar to Pentax K-mounts, HD or digital lenses have contact points allowing for auto aperture, etc. and/or ID of the lens itself to help set WB, while older lenses are as designed, fully manual, with aperture control.
However, even Leica changed to a different T/L mount for its T-series and S-series cameras and then provided an overpriced $400 M-mount to T-mount adapter to use M-glass in the T/L series cameras. Pentax did not do that at all. The K-1,in crop mode will handle all DA K-mount glass (albeit in a 15.5mp K-5ii resolution), but to Pentax's credit, the compatible backward ability of the K-1 series gives it a symbiotic connection to the APS-c foundation that Pentax developed over 2 decades of digital camera bodies.