>Simple rule: if you accept unlimited liability you get free speech. If you don't you don't.

I don't recall where in the US Constitution free speech is defined as only being granted in proportion to legal liability. I only recall the part where "Congress shall make no law (...) abridging freedom of speech."

I know some on HN hate advertising in all its forms but there's no way around this - you can't make advertising illegal without also essentially making free speech illegal. You can regulate advertising, of course, as you can regulate speech with libel and slander laws, FDA labeling requirements, etc. But you can't ban it outright. And you certainly can't have inalienable, natural rights be contingent upon legal fictions.