Marriott used to have rolling tier qualification, probably about 3-4 years ago. They removed it because they said it was too complicated. Which it was since you would stay a few days at a Marriott but your status counter would go DOWN because you lost a week you stayed at a Marriott a year ago.

Hilton is implementing it with spiffy charts which allow you to see how many stays/nights/points you need in any given period to qualify/requalify -- if Marriott did that it probably would have worked. Maybe the competitive pressure will bring it back.