Kinda dumb point, since a healthcare worker is the one who gave me my single surgical mask in the first place. They don't want you to "donate" back a single used mask that your doctor gave you in the first place.
I don't think anyone is suggesting that you donate used masks, but you make a good point that we shouldn't assume that someone wearing a professional-grade mask is wearing one that should have gone to a healthcare worker.
They also don't want you to keep using a single mask for weeks on end, which is likely worse than not wearing anything since they're a breeding ground for bacteria. They aren't designed to washed, they're supposed to be disposable.
You can actually sanitize and re-use masks by baking them at relatively low temperatures.
"If your mask is not made of flammable material, Lin said, you can try putting it in an oven for 30 minutes at 158 degrees Fahrenheit, because the coronavirus is fragile. Doing so can kill off the virus, and “it doesn’t destroy the mask very much,” she said, adding that hanging the mask above a pot of boiling water for about 10 minutes could also help with killing off the virus, but it would need to be air-dried afterward."
Of course. But worse for who? The mask is at least partially to protect you from my probably not corona-virus related occasional cough (unless that bad cold which has left my lungs weak I had in January was covid), which is possibly spreading a bunch of non covid shit around every two weeks in my only public outing to the grocery.