I think you are right about what reginr was saying. However, my guesstimation of pgmusic's is a little bit different. I think pgmusic's real track's process requires a human ear, a musical ear. IIRC, A year or couple back there was a request on this forum for people to help with development, some computer expertise with a musical ear etc, but in retrospect it was probably for realtracks. Anyway, looking at how acidized wave files are created, the process is always helped by a human tweak. This is likely the same for realtracks. I don't think the process is completely automated. At the same time, I think reginr's idea is valid. It's analogous to the secondary market in regular styles. How big did that really get?
Any internal process is "proprietary", but as I stated I don't think pgmusic's brand value, or product value is enhanced by a closed standard. If third party sampling disks were suddenly realtracks compatible, I don't see BIAB users fleeing, I'd guess there'd be some enhancing to BIAB's value as more styles would be around. Perhaps there is some enhancement to the BIAB brand image by the notion that realtracks are advanced and exclusive technology. Wouldn't be the first time a company claims something like that.
I think history has shown that opening a standard often helps the creator. Look how VST has helped the publishers of Cubase.
I wouldn't be surprised if BIAB 2011 or 2012 or 2011.6666 enabled users to create their own realtracks.

Just my speculation, don't trade derivatives on it.

Finally, I have found a cool signature with sufficiently dry humor.