Adding 10 friends to profile should not be required for default Mega achievement
The "Mr/Ms Popular" achievement (Add 10 friends to your social profile) should not be a requirement for the "Master of X Wiki" achievement. Many smaller wikis don't have 10 active editors to begin with, and editors might not be willing to send/accept friend requests for various reasons. Friends are also global (e.g. you can get the achievement from having 10 friends on a different wiki), so it's not an accurate reflection of one's activity on that particular wiki.
Assuming it still works, you could get the achievement by sending and cancelling requests to the same person 10 times, but that's probably something that many people don't know about and defeats the purpose of the achievement anyways.