And that is just outright rubbish! IE works with most websites IF those websites are written correctly. It is just lazy programmers that do not make their websites code work with IE or any other browser for that matter.
Take any website you like, run the W3C and HTML working group tests and see how many errors, violations and warnings are generated. Then access those websites and run debugging tools available on your browser and correlate the errors reported with what you find and almost always, you will see it is the code that is the problem, NOT the Browser per se.
But why am I telling developers how to do their work? I am just a layman that is fast learning everything there is to know about html5 code.
The argument is always, "does not comply with standards" But IE 11 is according to the evaluation site the most compliant version yet and better than many browsers out there.
I am accessing MYBB from IE 11 and I have NO issues with MyBB at all. So that shoots your blanket "It's (sic) doesn't work" down in flames.