Comment by jrochkind1

I haven't been able to see it even setting Chrome developer tools to crazy slow network speeds. Maybe chrome developer tools simulation isn't enough to see it?

The observations you are reporting are from images you created yourself and you know are in fact progressive jpegs? (not "regressive", although that's funny). There are of course other techniques to start with a lower resolution image that do "work" (in the sense of actually displaying a lower resolution image first at least).