When 122 countries unite - no matter what they're uniting on - you can't ignore them.

Sure you can. I'm doing it now. Just like all the countries with Nukes will.

And yet, at the time when slavery was a thing, everyone was saying "The ones who want it stopped will never be able to make that happen." You have to think of things on a historical continuum instead of looking at a single treaty and saying "That didn't do the whole job, so it's worthless." Politics is about a lot of small, incremental steps. And this is one of those steps.

You ignored all the stuff that debunks your argument. You're trying to generalize around something that has a very specific difference. This is a question of military might. WW2 era gas ban didn't stick. At no point in history can I think of ANYONE saying "Use bows and arrows, not guns" to a country that had guns and it actually working.

Just because it makes it EASIER for you to argue if you generalize around that big wall in front of you doesn't make your arguments correct. It just makes you intellectually dishonest about the nature of power politics.