"people often select purifiers based on their maximum flow"

I don't know if that's really true. Looking at the top 20 or so Air Purifiers on Amazon, almost none of them mention the CADR or flow in the title, and very few of the reviews mention it. Most talk about sound, "HEPA", "ozone-free" etc.

My guess would be that people care much more about physical appearance than maximum flow. I would personally not tape an octagon of dirty air filters to my ceiling because that would be look ridiculous and probably not filter as well as my beautiful, silent $200 Winix box.