The problem is not being big but the effect you have on the market. And that effect is naturally a lot bigger if you are a defacto monopoly ergo why there are a

The problem is not being big but the effect you have on the market. And that effect is naturally a lot bigger if you are a defacto monopoly ergo why there are a different set of rules. It can't be all party if you are at that position. If you would not have that kind of control (and fines when they break those rules) it would be virtually impossible to beat these kind of entities or they can use their weight to strong-arm them-self in a lot of markets. See what happened in the past with Microsoft.