Not a Google fanboy by any means, but couldn't this be read with the opposite conclusion as well - that the average time that Google keeps marginal products alive is 4 years? Of course it's possible that everyone has some personal favourites amongst those 164, but if an idea really has legs what's to stop people from exhuming it from the Google graveyard?
It's probably more like a year with actual support and updates, two years where it's left to whither and slowly die, and then a year of notice before sunsetting it.
As much as I hate Google sunsetting products, I hate even more the companies that keep their zombies shuffling along in a state of undeath forever.