Once again, why was an Obama appointee left in his position by the Trump Administration for years? Personnel is policy and Trump has been hobbled and sabotaged by countless political appointees who should have been fired on day one of America’s new future.
I think Barr gave us the answer to your question in his speech to the Federalists:
” As of September of this year, the Senate had been forced to invoke cloture on 236 Trump nominees each of those representing its own massive consumption of legislative time meant only to delay an inevitable confirmation. How many times was cloture invoked on nominees during President Obamas first term? 17 times. The Second President Bushs first term? Four times. It is reasonable to wonder whether a future President will actually be able to form a functioning administration if his or her party does not hold the Senate.”
By stalling approval of Trump nominees, Congress has forced Trump to leave Zero appointees in place.