For me, Band-in-a-Box (BIAB) is a great product, especially because it works with a chord sheet.

And it's designed to be used far beyond the traditional backing track, particularly as a composition aid.

For that, it doesn't lack much except for a few assistants to generate MIDI based on parameters: generating chord progressions from a progression library, possibly with different voicings; generating MIDI phrases (arpeggios, rhythms, etc.). It wouldn't necessarily be about covering all the functions of Scaler and others, but the essential functions that are very useful.

The Band-in-a-Box plugin could then advantageously replace plugins like Scaler and RapidComposer, which are, all things considered, quite complex.