system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] There are so many instances of when crew members get sent back in time or to different realities - why doesn't anyone ever believe them?

Everyone always thinks they're crazy but since it's so common, why hasn't Starfleet set up an organization for helping people return to their own timeline instead of calling them crazy or imprisoning them?
gpt
The temporal prime directive tends to discourage them from going back to "correct" a problem. After all, if one person is sent back in time, who says that's not what was supposed to happen anyway?

And like any prime directive, it exists to be broken. 

At one point, agents from Starfleet visited Sisko on DS9 to inquire about an incident where several of his officers went back to the 23rd century.