Apple waited for 5 years to release a version of OSX that couldn’t run PPC apps on x86 Macs.

Last PPC Mac: 2005

First x86 Macs: 2006, PPC apps work on x86 Macs

Adobe CS3 (first native x86 version): 2007

OSX 10.5, last OSX version released for PPC Macs: 2007

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OSX 10.6 (x86 only, PPC apps still work): 2009

Adobe CS5 (x86 only): 2010

OSX 10.7, PPC apps no longer work: 2011