Well, yes, but DW hasn't dropped image descriptions of icons just because not all people use them, you know? As for people using animations in posts, I can control how those images show up or don't on DW. I think they all get placeholders or something? And the same for video content. (I find this very convenient because they take forever to load on my laptop.)

Again, I have no idea if putting in a ticky box would be difficult or helpful to users who can't deal with animations, but I think discounting it as a possibility because some users don't do image descs on their icons and probably won't check a ticky isn't the right reason to discount it.