I generally agree, just a small nitpick:

> Are you making sites for blind people? Use/support tools that are thinking about WAI-ARIA/semantic markup.

I think developers should always have accessibility in their mind. People (or organizations they work for) may choose to use IE8 and yes, it makes sense to draw a line somewhere regards to supporting browsers. They can decide if an upgrade effort is worth to use your application. However people do not choose to have less abilities and it's possible that they can't do anything to change that. I'm not a dictator who says everyone must use all the accessibility best-practices but usually there's a small effort which can be made with huge gains.