I think this is a result of their decision to disallow ALL communication with other players unless they are on your friend list. It's impossible to raid if you can't communicate. Since they have disallowed communication outside of friends, raids require people on your friend list.
Communication is key to raiding. With a game disallowing all communication except between friends, it greatly limits raiding.
Communication is key to raiding. With a game disallowing all communication except between friends, it greatly limits raiding.