A lot of blogs take advantage of free blogging sites like Blogger or WordPress.com to publish their blog posts. While this is free and easy to get started there are significant drawbacks to using free blogging platforms.
You Don’t Really Own Your Blog
When you blog at yourcompany.blogspot.com or yourcompany.wordpress.com, you do not really own your site. Google or WordPress owns the site, including all the links and search engine authority. Yahoo recently shut down Geocities, erasing everyone’s site. People who had sites at Geocities could take their content and start over, but they now have 0 links and 0 authority in Google. If you host your site on your own domain that can not happen, unless you forget to renew your domain registration. A blog is a valuable asset that you spend a lot of your time building up, so you want to have ownership of that asset.
You can get your own domain through a domain registrar like GoDaddy or Netfirms (7.99 for the first year). You then need to purchase hosting from a hosting provider ($100 for 2 years at Hostmonster). Host providers have simple programs that help you set up a WordPress blog on your site. You can email info@sparkplugdigital.com for help with this.
According to the book Inbound Marketing:
“Many blogging platforms or tools exist to help you quickly set up a blog. Whichever platform you choose however, it’s imperative that your blog not include the name of the platform in the URL of your blog for example blank.blogger.com, blank.typepad.com or blank.wordpress.com. The problem with keeping the name of the platform in the URL is that you are building authority for Blogger, Typepad, or WordPress, not for your company. We recommend having your blog address or URL be Yourcompany.com/blog or blog.yourcompany.com.”
It Looks Much More Professional and Credible
A blog on Blogger or WordPress often lacks credibility. When people see .blogspot or .wordpress in the blog’s URL, it often seems less credible than something like www.YourCompany.com. Blogger’s site design is often lacking. Using WordPress on your own domain, let’s you use unlimited options for your blog design, including many free professional designs. (WordPress is a free opensource software, not the same as WordPress.com).
You can contact info@sparkplugdigital.com for help with doing this yourself, or you can hire us to do it for you.
Charles Sipe, is a SEO Specialist for Sparkplug Digital. You can follow him on Twitter 
@charlessipe, or email him at charles@sparkplugdigital.com.
Unfortunately, building any kind of URL strength is a long process. Still, I believe you are quite correct. When you build a site, drive traffic to it and build some domain strength, that value belongs to you and is an asset to future endeavors. It just takes time.
Thanks!
MAS