Our right to free speech is not granted by anyone's consent or by government decree. It preexists the state and cannot be taken away.
We hold this truth to be self-evident. We are endowed by our creator with certain unalienable rights.
If any government becomes destructive of these ends, it is the right of the people to alter or to abolish it.
You can wax poetically all you want about endowment by the creator, but try saying racial slurs on daytime TV and see how long that lasts.
Advertisement is just another form of speech that can be limited.
What part of that are you confused by? You are making a brash claim that the writ of the state includes the ability to censor speech.
Your right to free speech is not granted by anyone. It's your natural right. It's not possible to separate this right from a human with a law.
It is not acceptable for a stranger to come up and start shouting at you while you're trying to read, or hold a conversation, do your shopping, or put gas in your car. So why is it somehow acceptable for advertisers to do so? Would you want to pay for a course of instruction, some unknown percentage of which was not instruction, but was actually conducted at the direction of unknown others, who, with no regard or concern for your life, liberty, well-being or happiness were trying to extract wealth from you? Yet that is exactly what happens with much of our media-mediated experience of the world.
I think the underlying changes in the technology of communication have allowed advertising to grow without sufficient thought on whether such expansion was actually a public good. Like license plates - the impact of which changed radically when the government could, thanks to advances in technology, use them to monitor the position of virtually all vehicles over time, instead of being forced to physically look up who owned what vehicle - the explosion of media over the last century has been accompanied by an immense shift in the impact and capability and intrusiveness of advertising. And it's legality needs to be reassessed in that light.