I disagree. As Marshall McLuhan said, "the medium is the message." Poorly delivered messages are prone to be lost as noise.

This critique is one of rhetoric - which is not what McLuhan meant in the concept contained in that quote at all.

Your complaint seems to be that the use of a sexual metaphor affects the ethos of the speaker in the eyes of some.

That metaphor is part of the message, regardless of whether or not you like it.

The article makes the assumption the creator's desire is to grow+grow it. It's only good advice is that's true, if the creator just wants to make some scratch, whilst scratching their own itch, then it wouldn't be good advice for said person.