@lori

That rule is true in the very mathematical sense: "A => B" doesn't automatically imply "B => A".

"If the sky is blue it means the sun must be up" doesn't imply the reverse ("if the sun is up the sky must be blue")

However the saying ir not enough, what's missing is "if it's a commercial product/service". That's important because if it's not then it's not happening, and if it's a libre software you can even take steps to *ensure* it is not happening.