You clearly didn't read the history properly. If it has nothing to do with Heroes, then why, without the same M&M1-8, is Heroes (all add-ons included, even the semi-apocryphal Chronicles) just a plot fragment pulled out of nowhere? Okay, then how, if M&M has nothing to do with Heroes, was Roland Ironfist freed? Where did the demons come from? Heroes is an integral part of the M&M universe. "If you disagree, your reasoning is emotional, not logical" (c) Greg Fulton, lead designer at NWC.
And also, read here (especially the last two answers) http://www.heroesofmightandmagic.com/forgetown/index.php?cat=interview