Face-to-face communication is mediated by a shared language, a shared space and time, and the social relations that bind the speakers. This has some advantages and some disadvantages.
Where normal space is closed to communication for physical or political reasons, virtual space can offer an alternative.
Where social relations affect what one speaker is able to hear/trust/credit another speaker is saying, virtual space can offer a more neutral ground. Virtual space can offer an anonymity (and leveling) that allows you to be heard when normally you could not.
This is not to say that virtual space is better than real space, just to note that it has some advantages.
Joanna