Are they, though? There are certainly some cases where it has happened, but I don't think it has been established that that is the norm.

Naive searching on the term shows that they common in PE, and they do have a worse default rate at 20% over 2% otherwise. Certainly something to look at more closely. And I would be nervous being party to one. That said, 80% success is still better than what some companies are looking at otherwise.