Quality is not the single factor, I know of a site that is wordpress based and only has 1 post and yet it is PR7-8 thanks to the size and age of the network it is in(major well known and well established Chinese site). It simply never got developed and has all but been forgotten, yet it's there.
The fact it exists at PR7-8(fluctuates) and is #1 for that article is enough to tell me that quality is not the end all of rankings. The "article" is just 2 sentences long and is basically a coming soon message.
I knew of a second such site attached to a wordpress template network of sites but that one got de-ranked about 2 years ago, it wasn't as old and had pr5. It happens.