Monopolies are bad. We know that. Oligopolies, where a few big businesses control most of the market, are also bad. So what factors make an acceptable level of competition, or what features flag an unacceptable level of complacent non-competition? It's tricky. I think it's more complicated than realising how much of the market is controlled by how many companies. Presumably, though, there's some number of companies required to make conspiracy untenable. I'd guess it's about twelve, the number of people we put on a jury in the understanding that such a group is too hard to sway as a whole. Whatever the number is, we need at least that many companies competing in every market to prevent monopolistic practices.
Mokalus of Borg
PS - Making sure that happens is going to be crazy-difficult.
PPS - Especially when someone creates a brand new product.