As a developer community, we need to get to the point where accessibility is not an afterthought, not even something that has to be considered at all; that just is. I'm stating this from experience; I'm blind myself, so I know exactly what is being referred to. My group used to use Slack, and we stopped using it for this very reason. It's not hard to fill out the accessible label field. If it's present in the framework, then it should be taught and enforced.