Earlier quoted context omitted.
If your standard for "conclusive" is "study must fork the universe to compare the same business with different timeline" then you may be waiting a while. Regardless, in this case, where the ongoing harm could be very large, we have to at some point go with the best evidence available.
I mean... people who go to cancer clinic have cancer at a higher rate than those who don't. Cancer clinics cause cancer. And therapists create mentally unstable people, etc. You wouldn't have to fork the universe. I think a randomly distributed trial would work, and could be reasonably made to work. Not sure though. FWIW, I think we should prevent private equity in lots of places, especially hospitals.
And what additional knowledge do you hope to gain versus a study design like this one that would be justified by the much larger expense?