Maîtrise des expressions régulières

Given how complex regex can be, I wonder what motivated Jeffrey Friedl to write a book that covers so many nuances and practical applications.

The explanations are detailed, but I struggled a bit with some of the more abstract patterns. Has anyone else benefited from applying these to actual coding problems?

The book spans multiple languages, and I'm curious about the process behind selecting examples that are both universally relevant and language-specific.