I like the one bad day take in theory because I don’t have an interest in Joker actually being some sort of nearly supernatural monstrosity. The important detail people generally forget about Scott Snyder’s Joker, who most people I assume are talking about when they bring up that type of Joker, is that he’s full of **** - he’s terrifying, incredibly dangerous, etc but that persona is something he’s creating and cultivating. Joker is a human being driven by something, we just shouldn’t be given more than maybe a hint as to what that truly is. Hell, Snyder’s Joker is even pointedly characterized as almost fragile and pathetic at times.
That’s probably the big thing that makes me love Heath’s Joker so much. How clearly he’s an angry, wounded person lashing out at the world no matter how much he talks about being purely about chaos and anarchy.