I agree that it's the universal application and expectation of monogamy that's a problem. There are circumstances that I can see monogamy as a good choice. Poly, in my very limited experience, does take an enormous amount of effort and commitment. Not just from you, but the group together, which is hard. It's like being in a rock band or something. When you have a demanding career or kids (or both) the effort you'd apply to being in poly tribe, for all of its appeal, can seem like too much.