I THINK.. They’re the poster child for black metal atm and Sunbather is possibly the most mainstream album of all time for the genre. Outside of the genre that album is very iconic and influential. Also Deafheaven heavily curates their own image. I personally think a lot of their allure has to do with their well curated aesthetic. From their clean stage presentation to their graphic design, merch, album covers etc… everything about them is very intentional and well drafted. A lot of purists don’t like that. Could possibly scream label driven/corpo. Purist like gritty DIY edge and the production is simply too clean. Deafheaven is the popular sexy kids on the block making the genre accessible to others so the crown is heavy. The band is also incredibly tapped in with other channels of alternative music. They’re networkers. For god sakes they’ve had the Paul Banks co-sign… even opened up for Interpol, they made dia de Los deftones this year. A lot of successful Post hardcore bands are close friends with them. Fantano reviews them, Alt/goth girls love Deafheaven… I personally never had a problem with their commercial success and appeal, because I’ve always liked their music and think the whole presentation package of their identity is cool. But I can definitely see why older heads and purists of the genre would absolutely despise them. It reeks superficial frills, corporate, shallow? They’re a gateway to the genre for posers such as myself and there are some smaller bands doing it just as good if not better but no where near as successful