That seems like bad advice. Your preferences are what they are. "Giving advice on how to become bisexual, or polyamorous" seems just as bad as "giving advice on how to become heterosexual, or monogamous."

Preferences can be quite complex.

Most people do like the idea of having sex with multiple people but might dislike the idea that there partner has sex with multiple people at the start. Being polyarmous needs specific skills such as dealing with jealousy that aren't needed to the same extend by people who aren't poly.

Some people are in love with a person who"s poly a person might want to become poly themselves to be in that relationship.