A person shouldn't be able to have signage above their business to indicate what it is, the phone number, etc? Not billboards, but literally a sign that says "Johnny's Bakery"

This seems a bit disingenuous. It's an advertising ban, not a ban on any and all forms of signage. In the pictures of Sao Paulo you can clearly see that businesses still have small signs out front, presumably with the name of the business on them.