Members participate in Xbox Community Ambassadors or the Enforcement United beta, and on the backend, we track your participation, calculate your XP, and award loot to your Gamertag as you level up. There’s no need to opt in to earn rewards, submit your activity, or create a new profile. We’ll take care of the heavy lifting.
Looks like leveling your gamertag was successful enough for Valve/Steam that Microsoft is jumping on the bandwagon too. I wonder how long until they add trading cards too.