I just don't get it.

[Jonny Appleseed]

2. From the perspective of the populous' response, chemical weapons being used is largely reactionary

Unnecessary cruel and inhuman as such. But from a militaristic perspective chemical weapons becoming normalized is a slippery slope, just like nukes. Imagine if everybody used chemical weapons. There'd be an arms race to make them more and more effective. That includes super-potent distribution methods like tainting entire water systems or wind currents. Imagine a type of sarin gas and distribution method that could spread it across an entire region. A radius of impact far larger than a nuke would create.

And that slippery slope continues because the methodological similarities in delivery between chemical and biological weapons are far and few in between.