The stigma was still there of being labelled as the first, true or not. Folks largely remember it as something introduced by the Germans, and later banned by international agreement.
I'm not going to go into the relativity aspects of chemical ordnance too much. As a military weapon it is much like many others, it kills or horribly wounds, and often not just the target. It seems the main reason to ban them was the psychological/morale impact, rather than actual military effectiveness. They operate more as a weapon of terror even on the battlefield. And there is also something psychological about killing all the living things from afar, but leaving structures, trenches largely intact. It drives some inate fears.
Submarine warfare was also something the Germans had been forced to rely on, particularly against merchant shipping. The inability of a submarine to abide by former naval traditions of course carried a large negative stigma, especially as viewed by other established naval powers.
Bookmarks