Because of something called A-133 (also the yellow book), audits of not-for-profits had become the Balkans of public accounting, generating much more complexity than they could reasonably pay for, unless you were a solepractitioner with minimal overhead.
She graduated from Bentley in 1986 and worked seven years for a solepractitioner, walking out when she realized that paying him a fortune for a bunch of clients that were as old as he was not such a brilliant business move.