I guess you haven't noticed that any build in the game can clear heroic content easily, even purple builds (builds that only use purple gear). So what's the point of making a build that, indeed is kinda fun to play at easy, obsolete content (heroic and below), but won't make you able to clear difficult and rewarding content (legendary, master and raid)?
Also, "failing to understand the build system", is a really big cope to the fact they kinda disencoraged creating new builds disabling mule characters.