Earlier quoted context omitted.
>But why are acquisitions anti-competitive? Because now there's less competition.
Instagram didn't have to sell. Less competition isn't the same thing as preventing competition. For example, imagine three restaurants competing. Two of them make an agreement with a common supplier to shut out the third competitor. That is what I think of as anti-competitive.
This is a “I’ll push you out of the market by taking a loss” behavior, similar to MS inclusion of IE in Windows.
Whether or not NS or SC was/is a good product is irrelevant. This is the behavior that antitrust legislation is supposed to stop. The law iirc does not require that prices increase directly; rather that customers be harmed (of which price increase is a possible expression)
The customers in this case are advertisers, and they are definitely harmed - there are now two online advertising venues, Google and Facebook, both making outsized profits because they are the only two games in town. (Which on its own is NOT illegal - but using dominant position to maintain it, as Facebook has done with e.g. Onavo, instagram, Snapchat) is anticompetetive.