Well, first of all, every bike has a wheel and a center of a wheel, so this allows us to mount Old Man Mountain racks on pretty much any bike with a thru axle. Additionally, there are a few other benefits:
All the weight is carried on the axle, which is the most secure, durable and lowest mounting point on the bike.
On eyelet-mounted racks, the bolts are in shear, which is fairly weak when stressed over time. Our axles provide a physical interface for the rack that is far stronger for carrying load.
Axle mounted racks can be used on suspension bikes and require no adjustment to suspension settings