From what I can tell, a lot poly folks won't try a relationship with someone inexperienced. It is understandable if you realize most of them got burned badly, and usually more than once
Within kink, it also makes sense that some are willing to work with a newbie and some aren't. It's their choice. If they are used to giving/receiving intense pain, I could see them not wanting to scale it back 20 fold for a newbie.
She might be picking up what kind of vibe/energy you have and making assumptions about what BDSM you would be into. In general someone submissive wants someone Dominant, so why waste their time with someone giving off a submissive vibe? Same for Dominants. Of course there are more roles than simply submissive or Dominant, but we often have a gut feeling whether someone complements us.