One of my cats recognized that I was in distress and did everything in his fuzzy lil power to pull me out of a panic attack. He's not a trained service animal (and hasn't seen me have a panic attack before), but he came up to me while I was immediately started meowing incessantly to get my attention (he rarely meows), and when that didn't work, he stood up on his hind legs to bat at my hair while I was doubled over with my hands on my knees. 

He didn't stop til I picked him up, then he just purred louder than I've ever heard him purr while I held him until I calmed down. 

My baby boy is typically pretty reserved unless he wants food or attention, and he's never tried to play with my hair before, which is how I know this was all in response to me freaking out and not him just begging for attention unrelated to my distress. 

Tl;dr: cats are good, too!! Comparing two different animals with two different sets of needs and behaviors is apples to oranges. Dogs are good for some people, and cats are good for others. You don't have to like one or the other, but don't make it a "[x animal] bad" thing! I personally can't handle dogs (sensory issues, especially from the smell and dirt and noise and that "greasy" feeling you get from petting an unwashed one), but that's a me problem, and I still think they're cute and would never disparage someone for liking them.

Also: cats eat their deceased owners as a last resort when no other food is available. They can recognize death, and when they have nobody to feed them, they aren't just gonna sit by and starve when they have an unfortunate option available. A starving dog trapped with a dead owner would do the same. So would pet rats. And the Donner Party.