C4596 Restrictions
As for strengthening the Miasma Breaking Pill, as long as one wanted to enter a place with poisonous miasma, they would need this kind of pill.
Under normal circumstances, even if an ordinary Martial Cultivator had a black stone, they wouldn't be able to buy a Strengthening Miasma Breaking Pill.
It wasn't that they didn't want it, but because they didn't have connections