Spotlight became an app launcher with the introduction of Mac OS X Leopard. App results were moved to the top of the list and automatically highlighted. OS X Mountain Lion didn't introduce anything new in that regard.Spotlight was an app launcher even in Mavericks. I was an Alfred user who found myself only using it to launch apps, and dropped it after Mountain Lion. With mavericks and yosemite, spotlight has become far more powerful and is enough for all my needs.
That, and I'd rather have fewer apps on my Mac.