It's a principle I'll call Kellner's Law: If a company makes a product or service available free or at a discount by involving advertisers, from the company's perspective that creates an implicit contractual obligation on the customer's part to see the ads; and any attempt to take advantage of the freebie/discount whilst avoiding the ads will be considered a form of theft, legitimizing any technical or legal means at the company's disposal to force customers to see the ads, or else to withdraw service from those who try to avoid them. Kellner's Law explains a lot of corporate behaviors in this space, including crackdowns by YouTube and other sites on Web-based ad blockers.
I named it for Jamie Kellner, a television executive who when TiVo (which famously allowed skipping ads in television programs recorded to the device) came out, said "Your contract with the network when you get the show is you're going to watch the spots" and that skipping ads with a device like TiVo was "actually stealing programming".