Funny enough, I plugged this into Google Docs to see if I could re-scale to give you a comparison of the given chart vs a 0-based, 5-unit-interval chart and it looks like that's actually what they used to generate the chart.
https://docs.google.com/spreadsheet/ccc?key=0Ag2TNlAslc4GdFd...
Apparently the automatic scaling gives you the 8-based scale you see in their post. (And apparently you can't manually re-scale a Google Docs chart.) Using "stack" mode (I don't actually know what this option does for a single-series chart like this) gives you a 0-based, 10-unit-interval chart. (Again, not sure if you can adjust this to any other unit-scale.)
Slightly different scale, but I don't think it's a significant difference (though the "television" portion does appear slightly smaller in the automatic scale).
Charts like these are always susceptible to scale-skew and perception, and even simple charts (like this) can be debated on those subjective measures.
https://s3.amazonaws.com/pix-media/TV+Categories.png
Why is the bottom line 8%? and why are the y-axis lines ate 8% intervals? No reason I can see.
Is it not obvious that starting at 0 and using intervals of 5 or 10 makes it easier for people to grasp the relevant information clearly?
</rant>