Were the drafters of international treaties banning chemical weapons stupid?

[Posteritatis]

8. They were only tactically effective a handful of times, actually

Chemical weapons in the First World War were responsible for a very small proportion of the casualties, and only had any kind of decisive impact a couple of times. The reason they were largely stigmatized is because they were not only militarily pointless, but they created even more horrific injuries or deaths than the conventional weapons at the time did. They "only" killed about 90,000 people in the war but injured about fifteen times that in particularly awful ways, despite being around a quarter of all the shells fired in the war.

By the time of the war - or at least by the end of the war - the sentiment was generally "this sucks enough without adding something to the mix that doesn't affect the outcome but just makes things even worse." The notion of a chivalrous, fair fight in general didn't survive the fall of 1914. They knew very quickly that things were different now.

Basically, by the end of the war they were written off as an unproductive atrocity (which was still perfectly okay to use against colonials, as the Italians particularly liked pointing out). By the Second World War they were much more dangerous, but it still came down to understanding that if they were used it probably wouldn't have an effect on the fighting as a whole save to make it even worse. When your only options are "have them used against you in return" or "draw down the wrath of the great powers," they get reduced to one of three things: an absolute dead end, a deterrent against foes who might also have them, or a weapon of desperation and/or fear. But really, that's all they ever were.