You technically CAN clone from a leaf using the tissue culture technique. You could end up with thousands of clones from one donor plant, but there's a catch of course.

You have to be able to work in a fully sterile hood with sterilized equipment. Basically, have access to a cleanroom or lab.

What growers usually refer to as cloning is actually not exactly cloning, it is propagation by cuttings, for which you need a whole shoot with nodes, where the undifferentiated cells that have the potential to form roots are.

The tissue culture technique uses just a piece of leaf and places it in sterilized agar, where cell division continues and the cells then over the course of a couple months slowly start growing an entire new tiny plantlet, complete with roots, stem, and leaves.

Google it! Very cool. I'd like to hear if any growers are doing this. Regular cloning is so much simpler though...