well the 24bit files typically need to be resampled and dithered down to 16bit (i.e. CD qual), before being able to make the CD. While what you say is true, in that most burning programs are very capable, they arent often capable enough to do those higher level processing steps. Chances are if you see a 24bit recording 'not for CDs' that the taper also seeded a 16bit version, ymmv.