I would say that Marriott Lifer is likely to have averaged at least 15pts per dollar spend, so if the average room is $150 per night then it is easy to get to 2M points on 1000 room nights.

Problem occurs with introduction of rollover nights and someone who stays heavily for last 2-3 years could end up with 1000 nights but have actually only stayed 500-600 nights and so be light on points requirement.

I like the rollover as it has meant that I have kept Platinum last year. I think I had 26 nights rolled over but it has made it easier to get one of the Lifetime requirements and with the reduction in the points requirement from 3M to 2M as well, lifetimers will become quite common and easy to acheive.