Companies can do this, there's no regulation against it and there probably shouldn't be any. But there are going to be consequences and they're probably not goo

Companies can do this, there's no regulation against it and there probably shouldn't be any. But there are going to be consequences and they're probably not good for the industry at large. Moves like this fundamentally change how much trust consumers have in SaaS apps. The risk factor of using new apps fundamentally changes, if ever so slightly. Unfortunately, this arguably works in favour of the companies that do this. By reducing trust in startups, there's fewer users who will take the leap on new actors. Twitter and Google wins by having fewer competitors, but the customer loses doubly so. If Facebook acquires every fifth social network, followed by immediate shutdown, users will eventually stop using them, hence less competition as a whole to FB.