Reassurance. Sympathy. Someone to "talk" to, as often as you wish and at all hours of day and night. All potential benefits of Twitter that may offer psychological comfort, but is the tradeoff of creating a public record of struggle and potential for damaging feedback worth it?
Social media isn't a replacement for real-world action -- it's a way to coordinate it. The fact that apathetic Internet users who plague our respective newsfeeds cannot click their way to a better tomorrow does not mean that dedicated actors -- those who would be in the trenches regardless -- cannot employ social media effectively.