Most treaties are only signed because the states signing them aren't affected by the treaty. Antarctica is not relevant to anyone, so its easy to get a treaty for it. On the other hand, the US refuses to sign the treaty that limits ocean borders, despite most of the world signing, and despite China clearly violating it. It would be an easy win, but the cost of being restricted is too high. Likewise, the nuclear non proliferation treaty was mostly signed by states that lacked nukes, and exception was given to states that already had nukes - the treaty is fluff, completely inconsequential, just political theater.