Other businesses are always harmed during the rise of a dominant business, that's what happens when a dominant business takes marketshare away from you. The question at hand is whether they took their share unfairly. In Standard Oil's case, the government found that they did, which maybe happened too late in Standard Oil's case.

But even though it takes time to determine wrongdoing, we still prosecute crimes after they happen instead of before for obvious reasons. You wait until there is evidence of harm to consumers. Maybe the government has evidence, this is just an early article after all, but again, it's hard to imagine someone unable to stop using Facebook or Instagram or whatever, there's a lot of social media out there.