Canon TSE Tripod Collar?

Maybe I'm too thick headed to see how this would help.

I'm assuming the TS functions of the Canon lens would suffice and you would not need the 'collar' shown on this site.

Can anyone 'splain why you might want it?

Thanks.

It appears that the lens mount will let the body move for shift movements rather than the lens, to minimize parallax error for multiple exposures to be used in a stitched image.
In the real world I don't know how useful it would be.

This is indeed a "luxury" item and I think it negates the need to reposition the camera body in relation to the lens when the lens has been shifted whilst shooting for stitiched panoramas. The body needs to move the same number of degrees (in the opposite direction) as the lens shifts in order to prevent parallax with objects close to the camera. I'd like one