While I take your point, the concept of telling a lesbian that they “just haven’t had the right dick yet” is almost always used as a slant to imply that they’d actually be happier if they were straight, not if they were bi/pan. It’s more saying “you’re wrong” rather than saying “you might enjoy something else in addition”.

Being bisexual myself, I find monosexuality to be pretty weird and struggle to understand it. I tend to put people who identify as either straight or gay in the same camp - as just not being open-minded enough to explore what feels like the natural state to me; that all people are potential sexual candidates. While it’s a pretty blunt instrument, I tend to think of the Kinsey Scale as being normally distributed - that true 100% straight and 100% gay people probably exist but are extreme minorities.

Again, that’s just my opinion, and it’s not one I’d ever levy at a person derogatorily. I just think as a species we haven’t yet come to the point of thoroughly and completely deconstructing the social and biological frameworks we’ve constructed around sexuality.