This has always been a myth. Snow Leopard had some massive changes "under the hood", and OS X 10.6.0 was very buggy, as can be seen by the release notes for 10.6.1, 10.6.2, etc.
What people remember fondly about Snow Leopard was in actuality the 2 full years of bug fixes that occurred after its release.
What Apple needs to do is end the yearly major OS release cycle. It doesn't leave enough time to fix the bugs before Apple engineers start working on new features for the next release.