When I hear the term “puritan” my immediate assumption is that the speaker has no actual knowledge or insight or experience regarding Christianity, Christian practices, Christian theology, or Christians as people. I assume the speaker does wish to signal a kind of non-christian lifestyle but simply has no actual clue.
I don’t think a lot of sex positive people argue “oh just do whatever don’t worry about it.” I think i hear more about safety, security and support within the bdsm community than from outside of it. Imo sexual curiosity is not degeneracy or deviancy, but honesty. Those dangerous things you mention are taken seriously, or at least most of us try to. Power dynamics, selfishness, etc. Can all exist in normal relationships too. Hell, even “kinky” (per se) sex can exist outside bdsm and it’s communities. I’m not going to say everyone has these urges, but many people do. Bdsm isn’t about encouraging people to do these things against their will, or force this lifestyle in any degree upon people. It’s being honest about what we want and what we enjoy and figuring out how to engage with it in order to be happy with each other.
If there’s abuse, it’s handled like in any non-kinky or non-sexual relationship.