To answer your question, I’ll just pose other questions to you -
what type of person seeks a job at the IRS?
what type of person gets promoted at the IRS?
Lots of good people go to work for the IRS, it’s a great place for a CPA to get their start. They leave and take that experience to their private practice where they use it to help their clients.
As to who stays and gets promoted, now that’s a completely different question.