They can be cloned at the protocorm stage, we just can't clone adult plants of known flower quality very effectively. Proliferate enough protocorms and you'll eventually hit paydirt. It's a good tactic for repopulating difficult-to-germinate endangered species, or for when you want a bunch of plants to sell of a cross that barely worked. For example, I managed to get just one protocorm of thaianum x Shirokane, if I had the proper hormones, I could turn it into 1000 lol. There's also work being done on mericlones from stolon cuttings, I suspect this is how the Mauds and Gloria Naugles are being cloned.