You use the term bark mix, but what about the same for sphag? Why use straight sphag?
Why not mix it up with bark?
It's not that orchids prefer one mix over another, it's the growers that have this preference.
Also ... its not the media that carries the success - its really the growers, (IMHO)
I've got catts in clay pots, full of roots without any media at all.
Sphag.moss is not for hobbyists who like to water more often. There's nothing wrong with that either. To some folks its' love!
If you like to pay more attention to you orchids, then perhaps a bark mix is the way to go