The dot.coms wanted to build their businesses on millions of users, but a decade later that has turned out to be far short of what it takes to build a successful social networking site.

UK-founded Bebo, this week put up for sale by incompetent parent AOL, has as many as 6 million ‘active’ UK users, about as many US in the US, and 1 million elsewhere, but its main problem is that this is a fraction of its main rival Facebook, which might have ten or twenty times as many.

It’s deemed a failure with millions of users in an age that needs hundreds of millions and is looking towards the first billion-user network. What you are not allowed to be in social networking is small, and having too many users from one country just looks like a cultural straightjacket unless that country happens to be somewhere huge like China or the US.

Bebo is undoubtedly lacking important features (parental controls have been a sore point), has too narrow an audience (pre-teens), and looks too small against Facebook and others. It is owned by a company without the development cash or intellectual prowess to put right these problems and arrest its falling numbers.

Facebook’s success suggests that social media built on free access could end up being a zero sum game, which values size and reach beyond notions of diversity that were supposed to be one of the Internet’s great liberations. We can get our news from anywhere and almost anyone, buy our goods and services on the same axis of choice, but in social networking we could find our choices are going to become more limited and controlled over time.

None of this matters if you see social media as naturally leading to monopolies. Equally, Facebook and Twitter are more than websites with user accounts and social walls. Increasingly, they area development environments supporting an eco-system of third-party software that is needed to make what they offer usable and useful. They are acquiring considerable latent power.

I have no idea whether Bebo is worth sticking with, but I doubt I’m alone in feeling anxiety at a world where a tiny number of social media sites control the whole market, pull ever more developers along in their wake, and scoop up all the dollars with them, not least from IPO investors.

Bebo might be inadvertently too UK-centric (i.e it didn't intend this), but couldn’t that be one its virtues? Other countries have their own social media specialist sites and I am certain that they cling on because they are not the corporate, faceless, US-controlled world of the US super-giant, Facebook.

The PC world made a similar mistake half a generation ago by ushering in an age dominated by another US giant and its Windows software, and the monopoly has not necessarily served the users well in the long run.  

Diversity is good in the long view, monopoly can cause harm. Facebook should not be the only path but one among a number on offer, but let's see if history repeats itself.