cause this is as nice "from the cosmetics" as the chronometers and it has a beautiful and reliable movement!
After 40+ years it is not for sure if the chronometers keep time within the chronometer range if they were not treated well...
On the other hand a well cared for non chronometer movement may keep time within a sec or two.
I think many collectors make too much noice about the chronometer rating.
It is an "uncommon" Seamaster version as Bill S. uses to say...
So enjoy your well kept beautiful SM and wear it with pride!
kind regards
Erich