On the Yelp thing, it's not just the negative reviews, the positive ones are completely useless, too, a lot of the time. And the reviews can be wildly contradictory. People on sites like Chowhound are just generally more knowledgeable and the reviews more consistent. You can find people who don't agree on one restaurant, but they're usually much more specific about what was wrong and what they didn't like and they tell you exactly what they had without the hyperbole that plagues a lot of Yelp reviews. And likewise they're much more specific when throwing out superlatives. I'd rather not to have to sift through review after review from people I have no reason to trust.
And allrecipes, I will always think it's the very worst recipe site on the planet. Sites like epicurious, Food 52, Chow, Serious Eats, Leite's Culinaria, just to name a few have actual tested recipes and usually from people who know what they're doing. Anyone can submit a recipe to Allrecipes pretty much. So, yeah, I think there's an astronomical jump in quality. Allrecipes is to me the Yahoo Answers of cooking --- it's just not a valid source.
But that's me and my snobbery.