The point is they do still have to have some basic level of figleaf.
If Carillion’s auditors had said, “This company is in the shit financially and hasn’t got a pot to piss in”, it would make it very difficult for even the most venal credit rating agency to claim that they had a AAA+ credit rating.
If however, the accountants say “This company is doing A-OK!!!” then when it defaults, credit rating agencies get to say, “We relied on the accounts”.
