Scott, God bless you! We're getting closer. So at least the incompatibility problem is documented in a reasonably reliable source.

Based on the fact that the first edition of the User's Guide, which would have gone to press much earlier than the final System release, contains almost exactly the same details as on the Guided Tour disk, I'm still not convinced it was an 11th hour discovery. I think like the manual, they most likely decided not to spend limited resources fixing it and along with the manual, released it as it was figuring it was close enough.

Thanks again. Anyone else who finds supporting or conflicting references please do post them here!