Replace companies with nobility or aristocracy and you're talking about a problem as old as civilization itself. The fact is, small groups with control over a lot of resource (elites) will always work to consolidate and secure their power. Barring some radical, unforeseen technology, the masses of people will always have a more difficult time coordinating their actions to prevent this. This is the class struggle narrative of history.
When was that?
Some of it has been overturned recently but limits have existed for periods of time.
Meanwhile, mainstream television is waning in influence for political advertising. Now it's all about Facebook. Think of the micro-targeting turnout power they have. It's obscene!