When I first read Snow Crash, I thought (perhaps wrongly) that there was also an advertising model to supplement the real estate business - and one that went hand-in-hand with it.
I love the passage that introduces "the Street", and it's the last sentence of it that gave me the impression of an advertising business model.
In the real world - planet Earth, Reality - there are somewhere between six and ten billion people. At any given time, most of them are making mud bricks or field-stripping their AK-47s. Perhaps a billion of them have enough money to own a computer; these people have more money than all the others put together. Of these billion potential computer owners, maybe a quarter of them actually bother to own computers, and a quarter of these have machines that are powerful enough to handle the Street protocol. That makes for about sixty million people who can be on the Street at any given time. Add in another sixty million or so who can't really afford it but go there anyway, by using public machines, or machines owned by their school or their employer, and at any given time the Street is occupied by twice the population of New York City.
That's why the damn place is so overdeveloped. Put in a sign or a building on the Street and the hundred million richest, hippest, best-connected people on earth will see it every day of their lives.