Plasma refresh isn't... the same.
Ok, here's the thing. Plasma has glowing phosphors, same as an old tube TV. In fact, a Plasma screen IS a tube, or rather a series of a million tubes (1920x1080 = 2mil individual phosphors!)
They're excited by a current, and they glow for a particular amount of time. The number of times a second they COULD be changed is the "refresh rate". I've got a 600hz subfield drive. Whatever. But plasma phosphors, like CRT phosphors, GLOW and have PERSISTENCE. So even if they are changed, it's super gradual and unlikely to tweak us out.
Plasmas DO have ordered temporal dithering, but it's much more wide-field, not individual pixels, so my brain in particular has no problem with it (although I know some people can't abide it!)