Once in a while. Some domains are reserved for certain types of organizations or folks residing in a specific city, state or country. Another rule to keep in mind is that some of your contact information must display publicly in the WHOIS database. But don’t worry. You can always opt for Domain Privacy & Protection when you register your domain name.
Just imagine Medium shuts down as did Posterous back in the days (which was a similar service). You will not necessarily lose all your content but all the SEO rankings you ever created. To get it right you need to publish on your own domain name and preferably on your root domain (www.yoursite.com/blog) and not a sub-domain (blog.yoursite.com). This has numerous SEO advantages. Why You Shouldn't Use WordPress! And Why WordPress is Bad
The primary reason I’m looking for an alternative to WordPress is its reliance on PHP. A language so awful I wouldn’t let it anywhere near my computer if I didn’t rely on WordPress for my blogging. Using PHP as the substrate for your CMS/blogging platform guarantees you’ll have day one security problems. Just look at all of the WordPress plugins and themes that have horrible security flaws (e.g., revslider).