Last week’s big business news was the announcement that Comcast, a gigantic provider of cable TV and high-speed Internet service, has reached a deal to acquire Time Warner Cable, which is merely huge. If regulators approve the deal, Comcast will be an overwhelmingly dominant player in the business, with around 30 million subscribers.

So let me ask two questions about the proposed deal. First, why would we even think about letting it go through? Second, when and why did we stop worrying about monopoly power?

On the first question, broadband Internet and cable TV are already highly concentrated industries, with a handful of corporations accounting for most of the customers. Once upon a time antitrust authorities, looking at this situation, would probably have been trying to cut Comcast down to size. Letting it expand would have been unthinkable.

Comcast’s chief executive says not to worry: “It will not reduce competition in any relevant market because our companies do not overlap or compete with each other. In fact, we do not operate in any of the same ZIP codes.” This is, however, transparently disingenuous. The big concern about making Comcast even bigger isn’t reduced competition for customers in local markets — for one thing, there’s hardly any effective competition at that level anyway. It is that Comcast would have even more power than it already does to dictate terms to the providers of content for its digital pipes — and that its ability to drive tough deals upstream would make it even harder for potential downstream rivals to challenge its local monopolies.