Yahoo! reorganizes the Y! Social API Guide, and added "YQL Social Tables" to docs, that reduces the number of HTTP requests and parsing of data. "Go ahead, page through APIs, pore through each elements table, make a note of every available query parameter. Deep inside, you'll feel happy knowing how much easier it's to join data using YQL Social Tables instead of making several calls to REST URIs, parsing responses, and extracting information with conditional constructions," informs Yahoo!.
Yes, you could use the YQL Social Tables before. But no one documented the tables, provided example queries, listed the available and required keys until now. Use YQL. Get social data. Enjoy.