It's also worth adding that this wording makes it extend beyond the US borders. If the US Constitution granted rights to individuals, it would only apply to individuals under the US Constitution. Instead, it makes a blanket assumption that the freedom of speech exists, and that while other governments may restrict it, Congress may not. For example, overseas funding for HIV/AIDS may not be conditional on recipients having a strict anti-prostitution policy, as that would violate the free speech of the recipients[1].

[1] https://en.wikipedia.org/wiki/Agency_for_International_Devel....