Metal is a broad canvas, and what most people consider "hardcore" is not so, it's metalcore, which is heavy metal inspired (inspired, see, not copying) by hardcore punk bands. Unfortunately, the terms have used interchangeably to the point of distortion. So the metalcore (which is, in itself becoming broader with narrowing down into things like deathcore for BMTH) you listen to is metal, along with the dozens upon dozens of other sub-sub-sub-genres.
People who cry "itz shit, not metal, lololol" are usually quite pretentious in their tastes, and refuse to associate with it. Doesn't help when the genre genuinely is shit, but metalcore has a few good artists that trve kvlt metalheads would probably like to murder.