I feel like the difference with Threads is Meta is owned by a much larger threat that can’t be trusted not to use Embrace Extend Extinguish in some evil genius way that ends up working.
Reddit’s owned by some dummy that did a lot of damage to his own platform but isn’t known to be smart enough or have the resources to threaten the fediverse.
Without any studies as backing, my best guess is “Dogs have owners, cats have servents”.
Alternatively: Dog thinks ‘Human gives me food and cleans my poop. Human must be a god!’. Cat thinks ‘Human gives me food and cleans my poop. I must be a god!’
And apparently cats have us psychologically hacked to adore them in multiple ways. Like how their purr is helpful for human stress relief.
Tl;dr I think it’s because cats own you back, and a narcissist would have an easy time hating them for that.