From what I understand, when you set up a new blog, you find a related long-tail keyword and buy a new domain preferrably with the name containing exactly the keyword and nothing else. This is supposed to help with Google ranking.
But if this domain is brand new, the ranking is not so easy to get any way.
So, why not use a generic domain that is, say over 6 years old and has lots of links to it already? Then just create a new keyword rich subfolder for every new blog and go, like: dating.domain.org or weightloss.domain.org or dogtraining.domain.org and so on.
My reasoning is that if you put more blogs on one domain with a history and create more inbound links, the domain should increase its rating and help the blogs rank better as well.
So, why buy a new domain for every new blog? What am I missing here?
Would appreciate your comments and experiences.