There's an important distinction that needs to be drawn here. It's perfectly okay to say 'we support modern standards, older versions of IE don't comply with m

There's an important distinction that needs to be drawn here. It's perfectly okay to say 'we support modern standards, older versions of IE don't comply with modern standards so if you use IE, you need to upgrade to a recent version'. It's not okay to say 'you can't use even recent versions of IE because we don't like the brand name'. (I think it is the former rather than the latter that people are generally doing, but it's worth clarifying the distinction.)