Demon Slayer: Kimetsu no Yaiba

[DarthEnderX]

If the toxin requires a significant amount of flowers to be extracted in order to produce usable amounts, those trees will be gone pretty fast and they will lose their protected areas at the same time. They also use the flower, not the leaves, which only bloom for a few months, so it's not like they can keep harvesting them throughout the year.

...then you grow more.

If you were running an organization of vampire hunters, you'd damn sure have fields of garlic planted.

There is also the issue of the expertise required to process these flowers. If only Shinobu and her team have the knowledge, skills, and tools to do it, it will be difficult to make it standard issue for every demon slayer.

Not sharing that knowledge/training with other hunters would make them MASSIVE assholes.