Gerhardt, in the podcast Hey Salespeople by Jeremy Donovan, says it's the complete opposite. The more you know, the merrier - in sales, you must have some level of knowledge and expertise.
You don't need to know cybersecurity like an I.T. person, nor you need to be an expert in all types of fabrics like a fashion stylist. Still, Gerhardt states salespeople need to be able to be like a tour guide or a concierge who can find all the correct answers and help consumers make the appropriate purchase for themselves and their needs.
Listen to Gerhardt talking about this from [00:05:41] to [00:10:02]: https://open.spotify.com/episode/24FhbNPZe88mIyjNM8Ys2Y?si=HzyHDuc6RTiS6mc9mt6CDA&dl_branch=1