Ummm... if there were no promos then we would book according the the quality of the hotels, price, and extra value delivered by the reward program at different elite levels in terms of hotel perks and free night value.

Which is basically what happens when there are promos, except that the free night part of the equation for a particular chain becomes more valuable.

That definitely prompts me to stay more. The last couple of years I've had top status with both Hyatt and SPG. Most of those are personal stays, including a lot of weekend trips down to Chicagoland that were pleasant and relaxing but by no means necessary. Many of them were during FFN and other stay-based free night promos.

In a world with no promos I'd probably make a lot fewer stays and renew in just one program because the free night part of the equation would be a lot less valuable.