That faq version is probably the worst.

Agreed, in general, though there are a range of variations on the "good" theme too.

The FAQ version is short and doesn't rely on look-ahead. Consequently it is the easiest to copy if you don't care how it works -- and easiest (IMHO) to understand if you do. Short and sweet has significant advantages if you are new to Perl, and that's why it's a good answer to a FAQ.

I did notice that the cookbook version you quote also appears (more or less) in the FAQ now.