This is a non-sequitur. The existence of private equity has an effect on how companies are run, not the other way around. Many well-run companies are targeted by PE exactly because they're well-run and have carved out a sizable captive audience for themselves. And when PE takes over, said company usually ceases to be well-run on all metrics except one.
PE exists because of the non-linear relationship between money accumulation and power. This effect means that it is more beneficial for any company to hoard capital as much as it can rather than "waste" it on the wider economy; after accumulating enough capital, the company can pivot away from whatever market it was in before and focus solely on asset management. PE mostly results from too low taxation on inert wealth compounded by zero-interest rate monetary policies.