The mystification is instant. WB makes a Joker movie to cash in on Batman. They get a cheap director and accidentally let him do his own vision. It makes a lot of money. Then they get lazy, decide to let Todd run amok with it, thinking it'll make money regardless. They cheap out on the usual corporate bureaucracy. The movie flops because Todd took it too far for general audiences.
But none of that actually happened, satanic WB executives are destroying western civilization by attacking Western Canon which somehow includes Ledger's Joker.