What I'm telling you is 100% true.
There were enough mites in that bag, that it wasn't a case of "hitchhikers". It was a SEALED bag of ZooMed forest floor, bought directly from Petsmart.
I as well used it for years without issue, and then had a massive mite infestation literally overnight. Not woodmites, reptile mites. I've kept herps for 15 years now, I know the difference.
I'm not relying on rumors, this was my own experience.