I have read this tired narrative quite a bit. Some of my groups favorite adventures since 5E came out were horror adventures. All modules off the DMs Guild of varying quality. Horror is an atmosphere that a decent DM can cultivate regardless of the system. Heroic or high fantasy does not preclude horror.
It's important to be clear about terms. When I say "horror gameplay," I'm referring specifically to a post saying that Ravenloft play should be about "feeling the limits of your character" and "it's a curse and a punishment" and "it's supposed to be a trap."
I'm pointing out that that kind of disempowerment is a clumsy fit for D&D mechanics...like hit points, or levels, or a 1-in-20-chance of miraculous success, or long rests, or Turn Undead.
Mechanics are metaphors, and some make better metaphors for curses, punishments, traps, and limits than others.
So I am saying that horror gameplay -- feeling cursed, punished, trapped, and limited, which is what the post I'm responded to is interested in doing -- is more than an atmosphere.
Atmosphere can go a long way, and you can still have fun with Halloween Themed D&D (I do!). But it's not wrong to say that choosing to play a vampire for fun or choosing to be cursed by the Dark Powers as a neat character option are mechanics that work against the feeling of being cursed, trapped, punished, and limited. Namely because they give you control and agency over the horrors that should be making you feel weak and hunted.
Dracula isn't really a story about how cool vampires are.
It's fine for modern Ravenloft not to lean into those feelings -- they aren't feelings D&D's mechanics really highlight. It's valid to lean into being monstrous heroes. It's a fun way to play that works with how people play D&D already.
It's fine WANT those feelings in your game, too, and to miss them when they are absent from modern Ravenloft.
My point is that if you want those things in your game, then you should probably look beyond D&D to capture them, even if you set your game in Ravenloft. WotC probably won't give us a version of Ravenloft that sells those feelings very hard. But, those feelings can still be found in interesting mechancis and injected into your games at home (even your otherwise standard D&D games!).