Ive read so much on this and here is my response for what it may be worth.
We humans always like to think we know more than plants. If your orchids grow well on pine bark in your climate and environment under your watering and fertilizing habits. I would continue.
Raw pine bark mulch is $3 fot a 3sq-ft bag

Its like most pharmaceudical information in the west. A lot of distracting and strategically worded "scientific" reports are put out by manufacturers of expensive bark products fir orchids so that we spend $7 dollar of a tiny bag of un-named 'treated bark".

Its a desease of our culture.

I have grown orchids everywhere and if you pay attention to the plant you can find what it needs to theive in your yard. It seems you have found it!