Flexbugs creator here. For what it's worth, all of these bugs have been fixed in the tech preview of Internet Explorer 12. Also, my co-maintainer (Greg Whitworth) is a member of the IE team, and he's been as adamant as anyone that we educate people on the shortcomings of older IE versions, so we can all build better websites.

This isn't about assigning blame, it's about empowering developers to be able to use flexbox today.