Speaking for myself, that "Joker" is being taken seriously at all by Academy voters is entirely due to Phoenix's powerful and affecting performance as the title character. Watching Arthur Fleck inexorably descend into madness and nihilism was really the best thing in an emotionally manipulative movie that's admittedly well-crafted, yet strangely and ultimately shallow.

And yes, Joaquin Phoenix is really that good. I've seen very few actors who've been able to successfully carry the dead weight of an entire movie on their backs and actually make it better than it probably and otherwise deserved to be. This was one of those performances, and had that role been in the hands of a lesser talent, the entire enterprise would likely have been remembered only as one of the year's biggest flops.