Virtual worlds and chatrooms

Chatting with previously unknown people is a common experience... in the real world. You can go to a cocktail party or to a mass demonstration, or simply walk on the street, meet people and engage conversation with anyone.
Naturally the idea arose (in science fiction first) to mimic the real world and allow this kind of conversation to happen online. Shared virtual reality is the telecommunication system enabling this.
In shared VR systems - also called virtual worlds when the decorum is persistent- a user is represented by an avatar and only sees a small portion of the world: the immediate surrounding of her avatar. Theoretically, there is no limit on how many people could chat inside a virtual world: user's perceptions are not saturated by the total amount of people talking since she is only aware of a reasonable part of the talk stream. Hence, one of the major problem of the chatrooms is solved: A virtual world never gives the feeling of being too crowded.
There are 1 billion connected to the internet. Imagine, that people spend in average 15 minutes a day chatting online. Anytime, that's 10 millions people connected and chatting. Mostly, they use instant messaging. But only a very small portion chat inside virtual worlds. I understand that chatrooms are not very compelling (see my previous post). But what's the problem of virtual worlds?
A virtual world can also become locally too crowded. It is not that the user feels it too crowded: it is a technical problem. Indeed, a virtual world is made of “rooms”. Each portion or zone of the world is supported by a server (see this) and when there are too many people getting inside a given zone the corresponding server is overloaded and the zone becomes lagged, unusable: too crowded. The actual technical limit for a zone is around 300 people and for most implementations even less.
Zones are like chatrooms. And hence the same rules apply.
Most zones are empty and remain empty (you do not go inside a VW to be alone) and non empty zones are soon overcrowded (their server are overloaded).
If you are not convinced, you can go and watch popular virtual worlds. Last time I went inside Google's Lively, I found thousands of rooms: sure, it denotes an attraction to virtual worlds. But roughly 20 rooms were non empty and the other were empty.
Inside Second Life the same is true. I do not have statistics but you can see that most islands are empty. There is perpetual struggle to attract people (with sex or whatever) and organize events to try to fill up islands. When somehow, somewhere, some event or place finally succeeds in attracting people, it immediately starts in repelling people because only 80-90 can fit in an island.
I am convinced that eventually virtual worlds will succeed as major form of real time communication and even replace or absorb instant messaging and telephone. But not if they are a collection of rooms stitched together.

Note: I should have said, instead, most virtual world are made of rooms. Twinverse is a virtual world that is not made of zones, it's a contiguous world. You would say I am advertising my company and I am.