I rip fabric on the cross grain, when I cut EXTRA wide fabric for "my in shop" customers and "online" customers. I cut 38" as a yard instead of 36" to be generous to allow for shrinkage when washing. It is also important to cut all 4 corners off (just a small corner)to stop the raveling, so when it is machine washed the fabric won't unravel. I know some say it puts stress on the threads of the fabric, but when you are cutting fabric for a backing for a quilt, you need it STRAIGHT!
Do you remember when we used to straighten the fabric by pulling a cross grain thread and then cutting it on that line with a scissors? That would be an excellent way to straighten your fabric without the stress of the tearing.
So that's how I cut the Extra wide backing fabrics in my quilt shop, because I need them straight.