I agree 110% with this. Free blogs are nice to play around with and learn... But if you're in it for the long-haul, you'll want your own domain(s) and own hosting. If you start out w/ free hosting and things go really well, you may decide you need your own domain w/ your own hosting so that you have more control on your site (scalability, custom 404s, etc.) When this happens and you need to switch, you frequently end up starting over from scratch promoting your new domain and getting it to rank again because most free hosts will not implement 301 redirects on your behalf from the old free site to your new domain's URLs.
I free blog is a great way to start out on. While learning how to promote, trying a new niche, besides many other ways before you go out in the world of making websites. It's a great learning tool.
Free blogs are great to ue and monetize, but I personally don't invest too much time into them as they can go away at a moments notice. I generally put much more focus on promoting the sites that I have have hosted under my control.
As I was new to all this; therefore, I decided to get started with a free blog. The selection of the free hosting service was another issue as I really didn't not have idea which is good for what reasons. Anyways, i too don't have plan to invest much time on it. I'm looking for getting a real start.
You'd of already made the money from clicks/leads/sales, so you'd buy your own hosting account and domain and carry on blogging.