I have two paphs in just hydroton in translucent pots with the bottom domes and drainage and the side slits but they are sitting on/in moist hydroton not in water.
So far so good.
I also have a paph in the same type of pot in hydroton and perlite and that is sitting in a dish of water and it is growing very well.
As to soil in orchid mix? I don't like it
I've actually seived bark before to get rid of the fine particulates and I don't use the premixed cymbidium mix available here because it is just full of dirt.