The auto updates software you're thinking of is Sparkle, and it's still going strong. Still by far the most common way for Mac developers to do automatic updates for apps distributed outside the Mac App Store. https://sparkle-project.org
Yes, but notification center, added in Mountain Lion, was an exact clone of the iOS 5 notification center. Which at the time was argued to be stolen(!) from Android's notification center design. So did Android steal Growls implementation, as well? That is what is being implied.
Growl and a particular packaging software that provides auto updates had basically become a prerequisite for Mac apps at a certain point.