But the Nifty has been in production for a long time whereas many of those 28-xx lenses were updated every handful of years...
Nearly every EOS body ever sold had one of the lenses I listed included in the box. Cameras like the 1D, 1V or 3 are almost insignificant.
Views of normality at an enthusiast site like POTN are skewed. We think the EF 50/1.8 is really common because so many budding enthusiasts pick one up as a gateway to learning about fast lenses. The reality is that the vast bulk of EOS users have probably never heard of it.
Typical EOS user over the years: Buy a Rebel (film or digital) with a kit lens (one from the list I made above). Maybe add a telezoom like the 75-300 (film) or 55-250 (now). And that is it.
It's worth recognizing that the population here at POTN is the exception, not the norm.