In practice, that means that normal commenters or people using social media aren't relevant for two reasons:
* There's minimal control over their actions from the 'employer'. There's some basic rules on what content is not allowed, but nobody says "you must write a question about Java every day". You can use the tools available however you'd like, and you have freedom over when and how you use SO/social media - there's no obligation to post with any specific frequency. That's not true for moderators: they have specific tasks they must complete, and they must continue to be active, or they lose their moderation status.
* There's no permanent relationship: you can use social media/SO once, leave, and return any time you like, and leave again. This is not true for moderators.