That's certainly a possibility, but I wouldn't put it at the top of the list without ruling out the possibility that they actually make money.
Where does the claim that PE debt is a loser come from?
According to one of the top links on google, state pension returns from PE investments is almost twice that of their stock investments if you look at 2000-2021 (11%/yr vs 6.9%/yr)
Those returns are completely different. Private equity assets cannot be easily sold. Try realizing that 11% return and you will quickly see it does it not exist. You need to take a substantial haircut to sell.
The managers of those funds make money based on deals and they move on before the deal goes south. Principal agent problem.
EDIT: lordnacho explains better: https://news.ycombinator.com/item?id=36751012