Probably a case of a monoculture of designers and/or developers on Retina Displays and Apple's renderer getting the benefit of extra pixels per inch of the usual font sizes?

This seems really common with tech companies that the fonts they like for "crisp" and "light" look great on Retina Displays and no one thinks to check any other display or OS font renderer. I feel it's also why the designers at so many companies right now often accidentally favor (display) fonts with hints and weight tuned for headlines, high DPI printing, and/or large uses (banners) for places where body fonts with thicker weights and better hints for smaller font sizes on less pixel dense displays would be much better for everyone involved.

(Though some of that belief that it is such a widespread problem comes from my bias from ugly personal experience of getting designs handed to me from the only macOS users in an entire enterprise and having to point out their font choices were entirely inappropriate on anyone else's displays in the company, and being the only one to point it out and easily ignored because I wasn't a designer and what did I know.)