Because 'deep state' does indeed mean covert, secret, sinister dark power in just about everyone's else mind. Specially gop and maga minions.
That is only because it's what Trump and his goons--the Steve Bannon crowd--want people to believe. Far too many are naive enough to do that. The Deep State is the administrative state. The government bureaucracy..
The bureaucracy Trump has said quite specifically that he intends to fire, and replace with his own people.