I'm a layman, so take this with a grain of salt, but here's the basic legal theory...
In antitrust law, intent matters. If your primary motivating intent is to make the market less competitive, that's what gets the book thrown at you. That's why it can be so hard to prosecute antitrust, because it's pretty easy to lie your way out as long as there's no direct proof of intent.
Let's take Facebook's acquisition of Instagram. Did they buy Instagram because they saw Instagram as a threat, or did they buy Instagram because they wanted to acquire their talent and improve their product? For a long time, you could argue it was the latter case, which warded off antitrust suits. Recently, some emails came to light where they explicitly talked about taking out Instagram because they were beginning to pose a threat. Now there's a smoking gun and a strong case to be made, which may well be prosecuted in the near future.
In antitrust law, intent matters. If your primary motivating intent is to make the market less competitive, that's what gets the book thrown at you. That's why it can be so hard to prosecute antitrust, because it's pretty easy to lie your way out as long as there's no direct proof of intent.
Let's take Facebook's acquisition of Instagram. Did they buy Instagram because they saw Instagram as a threat, or did they buy Instagram because they wanted to acquire their talent and improve their product? For a long time, you could argue it was the latter case, which warded off antitrust suits. Recently, some emails came to light where they explicitly talked about taking out Instagram because they were beginning to pose a threat. Now there's a smoking gun and a strong case to be made, which may well be prosecuted in the near future.