I don't know if early check-in is part of that benefit or not. But I do agree with MsEverywhere that a lot of hotels do try to get you into a room as early as possible.

A number of years back, I checked-in to the Santa Clara, CA Marriott around 10:00am. They were very apologetic that there wasn't a room available yet. The manager came out and gave me a couple of tickets to the Theme Park close by and had someone drive me and pick me up. I thought that was pretty good service. ^