There are disabilities that can interfere with ones ability to interact with people, there are disabilities that can interfere with ones motivation and executive functioning(or bouncing back), there are disorders that can cause paralyzing anxiety ect.

Also disabled people are individuals, Just because one person with a specific disability can do one thing does not mean someone else with that same disibility can do all the same things it depends on the individual and how their specific symptoms/issues interfere with their ability to get and keep a job.

And finally the notion that mental disorders/illnesses are automatically less disabling than physical disorders/illnesses is certainly not something that is helpful to people disabled by their mental disorders/illnesses.