Why economists and academics run into PR trouble!

Couldn't the economics professor have figured out a better way to convey the point instead of saying:

"With the exception of—possible exception of—prostitution, I don't know any other profession that's had no productivity advance in 2,500 years," he says.

And guess where he brings in this contrast? In the context of discussing online education!
Of course, my immediate thought was that through online prostitution gets the biggest bang for the buck; isn't that productivity? ha ha