Nope. Can't effectively glue leather to leather here. Always some type of textile used. It is what the machine is designed to use. Not sure if you understand 100%. The welt IS leather. The welt is just sewn to a piece of textile that is glued to the insole. The welt IS leather, it's the FEATHER that is textile. In hand welted shoes, the feather is created by scoring a piece of the leather insole and the welt is sewn to that.
Goodyear just eliminates the step of hand-creating a feather by scoring the insole. Instead, it uses a piece of textile glued to the insole by a machine as the feather.
You are correct, except that in earlier usage of the Goodyear machine method they sill used the carved leather feather.