Yes we do!
Wide backings are wonderful for long arm quilting because they will have few (if any) seams to contend with on the bottom of the quilt.
The quilt backing (as opposed to the quilt top) is attached to the long arm directly and pulled taught on the top, bottom, and sides throughout the quilting process to avoid lumps and pleats. The pressure on the seams, while not extreme, is something to consider.
Occasionally on pieced backs, multiple seams come together on both the back and the front in the same spot - causing a buldge or a jump in the stitching. Wide backings eliminate this possibility.