These services can host your content on their servers free of charge, but in exchange for that zero cost, your online destination will have a less-than-elegant domain, such as jeffreylwilson.tumblr.com. That might be fine for a personal blog, but it will look too low-rent for a business that wants people to trust it enough to pay for whatever it's selling.
Blogs are swell, but sometimes you need a simple place to park your persona on the internet for branding purposes. In this case, you can just get a nameplate site, or as we prefer to think of them, a personal webpage (rather than a multipage site). Instead of linking internally to your store or other pages of note as you would with a more traditional web page, a personal site usually has links that go elsewhere—to your social networks, wish lists, playlists, or whatever else is linkable.