1/2 Support.
But this is how I would like it:
When you click a player on the leaderboard, 2 options come up "Report User" and "Send Request", if the player has partying enabled, 3 options would come up, the extra one being "Invite to Party".
I support this if the game creators have the ability to turn it on/off, and by default it's turned off. Also the ability for users to turn it off themselves.