A new trend in PE is rolling up smaller businesses - I have been reading a lot about this. Doctors, plumbers, etc. The joke is that if you graduate from HBS and go to run a plumbing business people will look at you like you are crazy, but if you do it as part of your job at a PE firm, you get a lot of street cred.
We had a major leak in our apartment and our insurer had ServPro handle it - they specialize in cleanup and restoration - it is a roll-up of a lot of small businesses that now has a few thousand locations and is owned by Blackstone. They work relatively seamlessly with insurers which makes life easier for all parties involved.
I assume the angle here is what you mentioned at the end - there are efficiencies from a back office perspective, negotiating with insurers, IT, purchasing supplies, etc. If you are a doctor who likes practicing medicine but not the business side of it (which I don't think they really teach in med school), it allows you to focus more on your core competency.