It is to do with having a positive experience and reliability, it's not the the cost!

I use Song Master Pro almost daily which include stem splitting among other valuable features that is not found in biab.
The fact that I can reliably switch the computer on, double click a .bat icon and moment later I am immersed in learning a song, without issues, day in day out, it's a great experience, which unfortunately is not happening when I start biab.
Sure, I can use biab ok, if I don't use a feature that is meant to be used. This is not a good experience for me.