Like hanoz says above, what professionals wear is not really comparable to what people wear on the subway these days. It's the cheapest of the cheap Chinese crap, and usually used so long and mishandled that it is becoming really fluffy. Especially now that nobody really cares anymore and the use of them is incidental they end up being lugged around more than worn and not frequently replaced.

A fresh mask doesn't shed a lot but I've seen ones that are all hairy and stringy from being rubbed around in pockets with other stuff. I'm sure they shed a lot more material than a fresh mask.

And a lot of the types you mention would not wear masks like this but powered respirators (e.g. people working in clean rooms)

Personally I have major issues the masks for past medical trauma reasons but I really don't think they are healthy to keep around forever.