[noloqy]

This was a badly chosen example indeed: in many countries lawyers are obliged to continue studying and completing tests throughout the career. In fact, one of Holland's most prominent lawyers got suspended for not obtaining enough study points for an extended period of time.

Anyway, in a sense I agree with the author. To stay sharp programmers need to get out of their comfort zone. There's multiple ways to do that; side projects is one of them. If you don't get out of your comfort zone, you run the risk of becoming like a pilot who forgot how to land or take off, because you have only been flying mid air for so such a long period of time.