No-www.org strives to make the Internet and communications about it as fruitful as possible. To that end, we make the modest proposal that website makers configure their main sites to be accessible by domain.com as well as www.domain.com.
Our ideal scene is one where non-specialized sites accept traffic on the www host name, but silently redirect it to the bare domain name. This is what no-www calls Class C. However, any site that takes in traffic one way or the other on both the www host and the bare domain are acceptable here.
We understand that this sort of configuration is not appropriate for every website. For example, a domain may require the webserver to be stored on a different machine than the domain root server. However, relatively few sites are built with this sort of architecture. A properly wielded DNS config can allegorically move mountains and make a setup like a Class B fairly simple even for the biggest of websites. In fact, several websites choose to forward traffic from domain.com to www.domain.com for branding reasons and that's just fine with us. As long as they don't simply block all HTTP traffic on the bare domain name, they're OK in our book.