It sounds like folks are coming at this from two different perspectives... is Ravenloft a location, or is Ravenloft a theme?
Those that consider Ravenloft a location or a "setting" can accomplish any type of adventure they want-- with or without Darklord interference-- because so long as it takes place in or references any of the domains that the campaign book identifies, the qualities of the people, places, and locations reflect the domains as written in the setting book, and most of the tropes that the Ravenloft book gives to us are followed... then you are playing Ravenloft.
But if you consider Ravenloft to be a theme of a game and not just a location where adventuring takes place... that's when
@Minigiant 's point take hold. Ravenloft is about cursed and evil dark lords forever being tortured by dangling what they utmost want in front of them but never giving it to them. Sisyphus in gothic horror. And the entire rest of the land and people that Darklord rules over are all there merely in service of the torture the Dark Forces have put in place to tantalize the Darklord. And anything you play that doesn't have that thematic thread underpinning the adventure, the characters, and the locations could basically just be considered standard Gothic Horror. Which is fine if that's what people want to play, but it's not "Ravenloft".
This argument is really no different than any other campaign setting discussion. Is an Eberron game an "Eberron" game if the Last War was not a thing and none of the Five Nations reference it or act as though they've just come out of it after 100 years and could see it all fall apart and plunge themselves back into it if their politics break down? Without that thematic underpinning is Eberron merely a generic magitech setting?
And this dichotomy is also exactly the same sort of thing that inspires some people to claim that there's "No difference!" between Greyhawk and the Forgotten Realms campaign settings because they see them both merely as "bog-standard generic fantasy" settings-- while completing ignoring or being ignorant of the politics and thematic ties both settings have that make their worlds distinct.
Deciding on how one feels about what campaign settings are meant to do will go a long way in determining which way you might look at it.