Yay. Glad that perspective helped you then.
I suspect poly <---> bdsm crossovers happen like they do because it's the same-ish sometimes in vibe...
poly sometimes can feel like edge play of the heart and sometimes body.
bdsm certainly is body edgeplay and heart edge.
I have decided yet how the mind/soul buckets fit in there if people are made of mind, body, heart, and soul.
I'm working on that for myself. (I tinker in my head a lot -- that's my fav playground.)