As of the current moment and past decade or two YES those genres of metal have been the most popular. As per being pop music yes they tend to follow the pop formula in terms of song structure they are not anti-music or overly experimental like powerelectronics or noise or grindcore or whatever John zorn is up to. Melodic metalcore 100% is pop music
That being said it's not a bad thing and I'd prefer these genres being the popular face as opposed to glam or power or nu metal (which held the 90s spot for pop music like glam did in 80s).
As for people saying "not true listen to methwitch" yeah id still throw it in pop compared to sore throats 22 minute fuck you to grindcore album disgrace to the body of side vicious which came out in 88 (and you will love if you love batshit music pushed to the brink) or anything by a group like whitehouse or merzbow. Hell I'd say curse of the golden vampire (alec empire + techno animal aka former napalm death) is far more challenging cybergrind that removes the pop elements completely.
In the end who cares and it's not elitist or gatekeeper but a statement of fact and there is nothing wrong with pop music or song structure OR being the popular face of a genre you fucks really want some manowar or poison or limp bizkit being the face of metal? Common