Hi,
Here's my take on your post in case it's useful
Realtracks do not specifically generate chord voicings. They are an audio file that are created by a musician who plays chordal accompaniments and/or melodic riffs. These audio recordings are then mapped to identify which chord occurs where within the track.
When a chord progression is typed into BIAB, BIAB uses PG Music's chord mapping to isolate the region of Realtrack that contains the required chord and then copies, pastes and seamlessly stitches that chord as needed. In this way, fragments of Realtracks are used to create a backing track. If you go to \bb\Realtracks and open any of the audio files there, you will hear the original audio recording.
Regarding using BIAB for songwriting, I use it all the time. In fact, I could not write the songs that I do without the software. The program gives me heaps of musical possibilities and drives me in very creative directions.
Some users on these forums prefer to use a guitar or piano (for example) to create with and then use BIAB to build the backing. That works them.
As I see it, at the end of the day, BIAB is a tool and how any of us use it depends on how we see it as being useful for our needs.
All the best,
Noel