I dunno, I feel like you and Tony are incapable or just unwilling to judge horror films on their own terms. Or to put it like less of an asshole (see Norville? I've matured!), we maybe just have different sets of priorities when judging horror. Neither of you seem particularly concerned w/ a horror film's ability to scare/unnerve and that's always my primary interest and my main basis for gauging the film's success.
To overlook Colette's performance and the film's visual flair (I mean, even the *treehouse* was creepy and cool looking but not in a traditional way) and everything else that critics and filmgoers are praising in favor of fuming over superficial similarities to other films or a lack of character development and/or traditional story form, well, maybe horror just isn't for you. I honestly don't see how the similarities in basic plot structure of "Hereditary" and "The Witch" diminishes the quality of either film. They're obviously very different films and were both lauded for their originality. Just makes you seem like you've got an agenda against the film (and/or modern horror in general) and had practically already formed an opinion before even watching it.
And again, the "Rosemary's Baby" and "Poltergeist" comparisons seem particularly lazy, especially coming from someone who's seen as many obscure films as you have. I mean, "generic spooky sounds in the dark ghost aspects"? The handling of the supernatural in "Hereditary" vs "Poltergeist" is like night and day. And "Hereditary" isn't even really a haunted house movie. By your rationale, every horror movie that involves ghosts is a "Poltergeist". And to write off "Hereditary" as just your standard horror flick + "ostensibly pretentious trappings" is just contrary hipster bullshit and you know it. Please don't turn into one of those old men who constantly rants that everything new is just a ripoff of everything that came before it- nobody likes that guy.