Just thought I'd post a supporting post to contrast the posts saying the move is unfair.
Imagine that Facebook wanted to have that functionality. They offer to buy the companies involved, but the companies ask for an unfair price ("1 million dollars!"). Should Facebook be compelled to pay that price? If they do not wish to pay that price, should they be forbidden from entering the market? Should Snap or Foursquare have a monopoly against any competitor that might be able to out compete them?
We can say that Facebook has a monopoly, but does that mean they should be forbidden from entering any new (to them) markets? We can say that they have a lot more money than their competition. Does that mean that they should be forbidden from competing? I don't think any of that makes sense.
I think what people are concerned about is the idea that Facebook will abuse their market position to compete unfairly. I think it's reasonable to fear that, but I don't think you can shut them down a priori. We don't have thought police yet. You can't be punished for something you haven't done yet.
If the argument is that Facebook should be punished for their past actions and forbidden from entering new markets, that's an argument that at least makes sense (I'm not sure I agree with it, though). I just can't understand any argument that says that lacking such a punishment, Facebook has to refrain from entering markets that they didn't create.
If we had such a mechanism in place, I think the potential for serious abuse would far exceed what Facebook has done to this point. In fact, I think we would be encouraging companies that act even more irresponsibly than the bad actors we have now in the market place. I can't really see an upside.