Here's a survey on blogging vs. social networking on teens: http://www.pewinternet.org/Media-Mentions/2010/Is-Blogging-a-Slog-Some-Young-People-Think-So.aspx Good to know before adding blog related domain names...
That's because teenagers are typically lazy. Blogs are too much like "work". Social networks are redundant enough to appeal to kids who have no desire to get up before 3 in the afternoon, plus you can pretty much automate most of it. Blogs are a 20th Century invention anyway. Welcome to the 21st Century. Hope you enjoy your stay. Close the door on the way out... Would ya?
That's like comparing reading a book and watching a movie based on that book. most kids prefer watch the movie than reading the original book. why because reading is a lost art I guess.