[NSFW] What's the Premise Behind Hard Vore?

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Now, I saw a thread about this from two years ago, but the question was never really answered and I felt like it needed to be.
 
What’s the premise behind the hardcore vore fetish? I’m not sexually interested in it myself, but I want to know the interest behind it. The premise of it all. Can someone explain it to me?
 
If you don’t entirely know, it’s stuff like this:  
(Warning, the next images can be extremely morbid and disgusting to some. View at your own risk.)
 

 

 

 
If I could get some information and explanations from those who actually like the fetish, that would be great. I have no interest in it, but I certainly would like to know all about it for some Psychology studies I want to conduct and research about fetishes as a whole. Please and thank you in advance!
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