The dark cultivation forces had actually only been brought up as a concept several decades ago, and were distinctly differentiated from the light forces, which had clear qualifications to run schools. The light forces consisted of the large state-run and private cultivation academies as well as some of the large sects specifically for itinerant cultivators.
To put it simply, the dark forces were a group of unapproved black organizations which illegally recruited itinerant cultivators and opened schools just for profit; they were like those small shops which didn't have food certification and made contaminated latiao.