Blanchard and Online Communities

I am finding it hard to see online discussions, forums and CMC groups a communities. I understand communities as existing in real life, where people who share similar interests and live in the same areas group together. I believe communities become real and strong when something happens to bring everyone together, when people help and are there for each other, regardless of differences, a community is formed.
The Cambridge Dictionary uses one definition of community as "people who are considered as a unit because of their common interests" (www.dictionary.cambridge.org) This suggests that perhaps, even online, communities can be formed.
Blanchard considers whether all CMC groups, including blogs, can be named as communities and suggests that to belong in a community, FtF or virtually, there must be a sense of community (SOC). She addresses whether this SOC can be found in blogs.
Although I am still unsure of the concept of online communities, I appreciate that having a sense of belonging online (whether in a forum, social networking site or blog) is important.
With regards to our own blogs, I do feel like I belong to something and can contribute to the group in my own way.
I am able to associate the four characteristics which Blanchard speaks of (researched by Mcmillan and Chavis 1986) which are involved in having a SOC;
My blog allows me to feel like a member,
I am able to speak my mind on certain views, influencing others and being influenced,
I am able to support others comments and views,
and there is a shared connection between myself and the bloggers I work with.
However, do I hold this SOC with these blogs because I already know the people I share my blog with in real life and have FtF connections with them?
Does this "community" and sense of "belonging" that we have created online only work because we already belong together in the "community" of our course and our friendships?