For the same reason they were persecuted in Nazi Germany; for being a burden upon the nation who drain more resources and productivity than they contribute.

It's pretty much a given that in 'socialist' and 'communist' totalitarian states, you at best ignore the disabled, or just... make them disappear somehow.

It's one of those funny, funny things. Where do you find the most buildings and services with disabled access? In the capitalist countries that you're told don't care about people and are just a few billionaires and their slaves.