Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
Holding people accountable means understanding them and their circumstances well enough to assess whether they can and should do some things differently, getting in sync with them about that, and, if they can't adequately do what is required, removing them from their jobs. It is not micromanaging them, nor is it expecting them to be perfect (holding particularly overloaded people accountable for doing everything excellently is often impractical, not to mention unfair).
But people can resent being held accountable, and you don't want to have to tell them what to do all the time. Reason with them so that they understand the value of what you're doing, but never let them off the hook.