Just because a fungus eventually breaks it down doesn't imply that it's "harmless". It can (and does) still accumulate in organisms and has many undesirable eff

Just because a fungus eventually breaks it down doesn't imply that it's "harmless". It can (and does) still accumulate in organisms and has many undesirable effects, including the human body. It can s easily end up in the food chain as long as it's not broken down, including areas where the fungus is not effective, which are plenty. The only difference such a fungus can make is that it could break down in certain pockets in nature in the long run.