I don't know Ruby, but the author's comments suggest that why_'s way is more brittle, longer, and slower.
How is it better then?
How is it better then?
You may end up with non-scalable, unreadable, and/or untested code in a production system for a number of reasons. Some I can think of off the top of my head include performance and schedule pressure. Introducing it for fun sounds like bad news bears to me.
The same applies for code.