It scales. I ran WorkZoo.com (Time Mag top 50 website of 2005 - sold it the same year) and we scraped over 500 job boards and aggregated the jobs into a search engine. A team of devs developed and maintained the regex for each board and I managed them and I wrote the dev tools they used to develop the regex for each site we scraped. It was incredibly effective and maintainable.

Incidentally, the dev tools I wrote were in javascript and they created regex that we'd test in javascript and deploy in Perl. The regex engines are identical which is why it worked.

Scraper abstraction is for people too lazy to learn regex. Get a good book on regex, and learn how to use Perl's s/// regex with the 'e' modifier. It'll change your life.