Here's the difference. When we talk about companies dominating an industry, we're usually talking about practices that keep competition from even forming. Monopolies are formed as a result of big companies buying out or making it impossible for their competition.

Steam doesn't do that, which is a big reason they won their monopoly suit. They just provide a better model than anyone else is willing to, and they rake in the cash because of it.

Compare this situation to books-a-million in the states. Books-a-million doesn't have a monopoly on books, they just have created a better environment for selling them. They aren't stopping other book stores from opening or buying chains to shut them down, they just sell you a cup of coffee and give you a place to sit while you browse their massive selection.

That's not a monopoly, that's just better business.