Couple of things. First, these two groups may or may not be mutually exclusive. Catering for the former may take care of some of the latter too. Second, this

Couple of things. First, these two groups may or may not be mutually exclusive. Catering for the former may take care of some of the latter too. Second, this question is actually very easy to answer. Catering to disabilities makes almost no money. Catering to IE9 gets the customers that forgot or don't know how to upgrade. That's a wash when it comes to advertising. Edit: Just to be clear, I'm not playing devil's advocate. I do my best to cater to people with poor vision for anything I write. That includes anything I use colour for. I'm simply answering the question as if I were the CEO of a company, where my goal is to make as much money as possible, and not care about anything else.