Service for whom? It doesn't serve the business - I'm sure they'd much rather people contact them directly - and it doesn't serve the customer - who wants to deal with a middleman when your toilet's overflowing? The only one served by this is the middleman, who gets to hijack leads and extort businesses.
The value added over a "dumb" directory is that you can use ratings to inform your decision instead of taking the service provider's word of being "the best in town".
I'm not making this stuff up, tons of people use Yelp, Zaggats, GetSatisfaction, etc so obviously they're seeing value somewhere.
I use Yelp all the time, so I agree with you that there is value in a directory with ratings. But the value of Yelp comes from the carefully crafted community that I feel I can trust, not from some random star rating from faceless people, and I certainly wouldn't get any value if Yelp stepped in as a forced intermediary if I wanted to contact the business (that would make me stop using it immediately, actually).
