A great number of Mac users refuse to upgrade to 10.7 or 10.8 because they still need to use the PPC software. When 10.7 was introduced Rosetta was abandoned and everything had to be pure Intel compatible from that point.
With OS X10.6 they still had Rosetta which allowed PPC applications to run on the Intel Macs. They enabled Classic Mode up to OS X 10.5.8 and after that it was abandoned. In 2003 Apple decided to abandon booting via OS 9 on any Mac they made. The two Macs that I had dual boot with OS X and OS 9 were made in 20. The 1.5GHz G4 PB was one of those that could not boot from OS9 but could use classic environment if operating with 10.4.11.
