The text of the Postal Clause in the constitution is just "The Congress shall have the power... To establish Post Offices and post Roads". I don't see how this

The text of the Postal Clause in the constitution is just "The Congress shall have the power... To establish Post Offices and post Roads". I don't see how this bars the US congress from being able to privatize the post office - indeed, I don't think it even implies that the US must have a post office at all, just that Congress definitely has the constitutional authority to establish one.