I came across this blog thing today. It's a bit tl;dr, but worth the read if you have the time. A lot of things I agree with.
I'm going to come out in defense of rules, though. I agree with the author on the idea that having too many rules can be a bad thing, and that rules trying to constrain somebody's emotions are ridiculous. There's a part where she talks about how it should just be basic human niceties, and you don't need specific rules in a relationship because that undermines trust and is just a subversive way to control the person you're with. The way I see it, though, is that relationships are complicated and you need to at least go over your comfort levels with certain activities. Because in the end poly is still a relationship - maybe not the pair-bonded, "one penis only party" that's covered in the other blog - and it's important for healthy relationships to know and respect your partner(s). I like to think about it like any other preference. Analogy time! Let's say I like sushi (because I do), but Frisbee isn't keen on it (because he's not). So in our relationship I might not ask him to take me out to restaurants where they only serve sushi, because I know it's not something he likes. But it would be silly for him to expect me to stop liking sushi just because he doesn't, to not go out for sushi with others, or to even enjoy getting sushi on my own.
Now-hubby and I started putting a parenthetical on our relationship rules after awhile: unless communicated and agreed upon. So, for example, we have a "no overnight" rule (unless communicated and agreed upon). The first night I met Frisbee I spent the night with him, but that was only because I had called Now-hubby and asked him first if it would be okay. I don't see it as constricting or like, "gee whiz I don't get to do what I want because you're such a stick in the mud with all these rules."
I see it as respecting the other person/people you are with. Is it important for you that you have specific sexual acts that you perform only with one partner? Then express that to your other partners. i.e. "I'd like it if you only got head from me (unless communicated and agreed upon)." When I was single, I knew there were certain things I was looking for in a relationship. Being open to poly was one of those things. Somebody who would be okay with telling me about their dates, and keep me in the loop on things like whether I was going to see them that night or not was also important. So it was my responsibility to communicate this, and make it a sort of "rule" for the relationship.