I assume handling character closure(s) gracefully would get you brownie points at the very least when applying for a subrace or MPC, most of which are visibly hostile/outcast type characters where conflict is assured. Being able to let go is basically a requirement for playing them after all.
Though by nonstandard/esoteric concepts you probably mean things that cannot be applied for, which I guess the server isn't really about.
I think that here, closure is meant to be entirely by choice and the reward is finishing the character's story. I assume the staff has some sort of position on that and does not want to incentivise doing it, because that would make it less special and done for its own sake. Any sort of guaranteed permadeath model would seem to work directly against this, even though it's the inverse, because then death becomes too frequent and not only is death cheap but so is life.
Technically, given hostile/outcast characters cannot be forcibly closured by other players; And .. As far as I'm dutifully aware, vaulting isn't permanent closure anymore either, as the respawn system now exists, the only way a character can get forcibly closured is by Strahd himself yeeting them into Castle Ravenloft. At best, you can be given a forced shelving by being thrown into the Vault or corpse-hidden in such a fashion that you are forced to wait out the timer before paying XP to respawn.
For some people, that might be satisfaction enough to finish their story. But if you're looking at it pragmatically, or if you've played on this server for an extended period of time, that becomes less appealing as a concept, depending on just how invested you've become, time-wise, into their trades and crafts. To put it in a moment's perspective, let's say that you're playing a character who hasn't had a significant domain-based contribution to their history, and doesn't really have a story, so-to-speak. A lot of characters do not have a defined narrative, or opportunity to find one in a greater plotline, and instead exist in a mélange of dungeoneering and slice of life social roleplay.
If you've spent... A year, on your character, they're nearly level twenty, and you are looking at starting another character, what's to stop you from coming back to your now, max-level Druid, or Wizard, or what-have-you, later down the line when new changes come to the server that you're interested in exploring, dungeons, or otherwise events, conflicts, or... Simply just boredom of your concept. There's a lot of security in keeping your high-level character in a back pocket to play when you'd like to experience the other end of the server again. Sometimes you might have multiple said characters, if you've played sufficiently long enough. That's what I believe is the majority experience for players that I've encountered who do gain high-level PCs, but aren't say, a native to any domain.
To put this in perspective, I have a high-level Wizard, a high-level Bard, and .. Honestly, if the respawn system had been implemented back when, I could've had a high-level Paladin who would have been ripe to take advantage of the Blackguard Fall mechanic that got implemented, as he was fallen; He was only closured because I had no particular belief that he'd get out of the Vault. So his closure spurred me to my next character; But if ... I could've just hit the respawn button after six months? Why not? ¯\_(ツ)_/¯
What actually benefits me from doing that? Why would I logically want to?