Brought up the same poiny after the WoT panel at Nostriga.
Just replace hyped up terms like WoT with what people actually mean with it: your network.
Given the fact that newcomers don't have a network, their network cannot be a valid entry point. So then you're left with someone else's network, which sucks since it's catered to that individual and not to you or some kind of niche interest you have.
Communities however make it the Admins job to cater to those niche interests and serve as perfect entry points, given their focus and interoperability with other overlapping Communities.
Open question to me is still:
What does it technically mean to **belong** to a community?
Maybe that you've had a relationship status event issued by the community moderator.