The only conclusion you can draw that would explain why both the legislative and judicial branches have voluntarily ceded their own power, their own checks and balances, to the executive is because -- ta da! -- they've all been in on the whole thing. For decades they've been short circuiting the checks and balances, calling it euphemisms like "fast track" or "eliminating gridlock", because they're in collusion in their desire to subjugate all things to the State. I'll go ahead and drop the C word: conspiracy. What we have unfolding all around us is a conspiracy hatched a long time ago. The various players and pieces of the puzzle may not have been in on it from the very start, but they've been gradually brought into the fold as necessary.
This conspiracy, it's not something we have the ability to discern with precision, but an inchoate recognition is enough.