HBO has long been the crown jewel of American television. It was HBO, in the 1990s and 2000s, that kick-started the golden age of television, funding and running shows like “The Sopranos” and “The Wire.” And it is HBO that still captures broad audiences with shows like “Game of Thrones.”

So it’s disheartening to see this venerable institution of pop culture wielded as a weapon by AT&T — HBO’s new owner since the blockbuster merger in June between AT&T (a telecommunications giant) and Time Warner (a media giant). Last week, HBO went dark for both DISH and DISH-Sling, the main competitors to DirecTV and DirecTV Now, AT&T’s television services. This brazenly anticompetitive strategy does not portend a happy future for the viewing public, or for HBO itself.

At the risk of saying “we told you so,” it was widely predicted before the merger that AT&T would use HBO and other Time Warner media properties in just this way. When the Justice Department sued (unsuccessfully) to block the merger last year, its case was premised on the idea that AT&T would use its ownership of such properties to hurt its rivals in telecommunications. And now it is doing so.

Post-merger, AT&T has the means and the incentive to raise prices on valuable content (like HBO or the coverage of the N.C.A.A. “March Madness” basketball tournament) for cheaper, “unintegrated” telecom competitors that have been saving consumers money. If its rivals refuse to pay up, it can withhold the content entirely, diminishing them as competitors.