I have creat some web 2.0 BLOGs, all those DA above 40. I have create user profile in other sites and drop my articles and their DA also above 40. I read many SEO articles, in those expert recommend web 2.0 BLOG creation. For me it is very confusing, What DA is there for web 2.0 though I'm getting the same to article submitting. Why experts recommend web 2.0 BLOG's, and why they are asking to submit website articles in tier 2. What is differnet between both engines.