Any sewing machine, even the smallest home type machine, will sew two pieces of upholstery leather together. You run into problems when you try to sew two pieces of leather with 1/2" sew foam attached to them together.
The thicker the fabric you sew together, the tighter the stitch will be if you don't adjust the machine to what you are sewing. That's not necessarily a good thing in most cases. Too tight a stitch can cut into what you are sewing and damage it.
No one lives forever, the trick is creating something that will.