Marriott has regularly offered points for linking your social media accounts. Three years ago they let you earn up to 2000 points per month via social.
In 2016 they gave out 84,000,000 points to 73,000 members (1150 points per member). Now they’re rebooting social earning, renaming #MRPoints to #RewardsPoints and will allow earning up to 45,000 points per year — which can transfer to 15,000 Starwood Starpoints.