It’s true that dermatologists can just leave and setup solo shops which made it more resistant to PE compared to other specialties where the ship sailed decades ago (anesthesiology, EM etc).
However, as the govt and insurance continues to setup more and more burdens on practice (billing, coding, emr, meaningful use, mips, etc) its harder and harder to cut a decent salary going solo.
In addition PE firms negotiate higher rates from insurance so these large dermatology mills can bill sometimes 175% for the same work a solo guy does who has no negotiating power.
Finally PE has enough capital to setup capture all the ancillary streams of revenue from self referral (ie in house path lab and pathologist, in house mohs, cosmeceuticals, estheticians, full battery of cosmetic lasers etc). So they end up paying a dermatologist probably more than they can get solo (unless the market is completly empty or the solo guy is working twice as hard) while still taking a lot for themselves. Of course this extra money is coming right out of patient pockets for similar if not inferior medical care.
No wonder this country is going bankrupt from healthcare expenditures....