Looks like Marriott worked on the "Reward a Friend" and it works again:
Up to 50,000 bonus points for you
Earn 2,000 bonus points for each stay your referrals make, up to five stays per referral. That’s up 50,000 bonus points for you.
Up to 10,000 bonus points for your friend
And your friends will earn 2,000 bonus points after their first five stays. That’s up to 10,000 bonus points total for them.