Dermarolling 4mm?

Can't imagine this hasn't been discussed before, but wasn't able to find much on it...
Recently spoke with a practitioner who stated he had a patient needling scalp at 4mm depth and had incredible results, surprised even the practitioner.  I've always heard recommendations for 2mm or less...Guess I didn't realize various hair follicles lie at various depths, from 1-4 mm, with coarse 'terminal' hairs lying closer to 4mm.  Searched online and couldn't find testimonies from anyone on the forums that  mentioned needling that deep...reasons being: fear of scarring, fear of infection, or fear of directly damaging hair follicles.  .5mm to 1mm is the most common, and most of those were just for better topical absorption.  My question is...if 4mm is depth of follicles for coarse hairs, why wouldn't needling at that depth be regenerative??  Assuming the negative issues can be mitigated (needling, not dermarolling to reduce risk of scarring, and excellent sterilization techniques, would this potentially be effective? Has anyone heard of anyone needling that depth?  Can't even find rollers or stamps that go that deep...(believe that depth is normally the realm of medical doctors, and not aware of any studies needling that depth).  Diabetic needles are the only thing available that would work I believe.  I don't know enough about hair structures to know if it would have a negative effect, but do have experience with prolotherapy needling.. My opinions on this somewhat stem from that. Had ligament laxity that no amount or experience with supplements was able to fix...stopped the damage process/inflammation, but ligaments heal poorly and nothing in the realm of physical therapy or supplementation worked to re-initiate the healing process, but had amazing success with prolotherapy...I know that for prolotherapy the dextrose injection must be exact depth and location of the damage in order for ligament regeneration to occur.  I assume it would be the same for hair regeneration... I'm considering trying it, but there's risk without knowledge...any opinions would be appreciated.