Sure, but a TV ad takes (at the least) and editor, or (at the most) a cast and crew. They take by money and time to create, and loop average working people into the process. Of course there will be people in any profession that will make whatever they’re paid to, but by and large, most of the acting/editing industry has some form of ethics.
People debunking false claims takes time too, but since creating them take time as well, things have a chance to balance out (obviously that’s happening less, but there’s still a chance for it to happen). But if an AI model can pump out fake history autonomously, almost instantly, and without any chance for a human with ethics to intervene in the process, debunking/fighting misinformation becomes WAY harder. Because you’re not fighting a person with limited time and resources anymore, you’re fighting a firehose of false content that will bury you without even breaking a sweat.