Does seeing other people suffer cause you to suffer? Probably, right? Unless you're some sort of psychopath who has no capacity for empathy. Therefore a stoic is encouraged to alleviate the suffering of others, when it's possible.

The idea that stoicism calls on people to ignore all the social wrongs of the world is a malignment of the philosophy. It's not fatalistic, nor is it isolationist. Somebody who is a stoic acts to improve the world when it's possible.