So, for example, a community (the social system) might use an email distribution list (such as Listserv) to communicate. There are those who would get confused and talk about the technology and the community in synonymous ways. One would join the Listserv list instead of joining the community. However, all this overlooked the fact that the group really had an identity of its own that existed completely separate from this sole communication channel, and could, in fact, meet through several venues. They might meet at conferences, have local get-togethers and socials, have teleconference calls, etc.
So, it became important to emphasize that the social system does not equal the communication channel. In fact, often social systems such as communities use multiple communication channels. Online communities, however, might only use one channel.