Well i would say it works more in the assumption that Yukkuris can all be corrected to begin with, which i would call it dubvious and as much not 90 of the cases reaching such advanced state of shitheadness.
It's rare for a yukkuri to change or truly get better if they had gone as far as a deibu, usually it's like a zombie mutation, there may be ways to "save" the infected in early stages but when it reaches and advanced stage....well.....make the poor bastard a favor and kill it.
anelaid if your pet goes Deibu, then something wrong happened in it's breeding, since it shouldn't, at least if you got a True Gold or Platinum, anything less is a gambit.
And as i mentioned, it's like a zombie disease, you just can't cure it when it got 100% Deibu.
Pretty much, just think about it, if you ignore the whole "living dead" part, you'll see it makes a lot of sense. Because if All the yukkuris were Deibus, it would be as bad as All the humans being Zombies, and we know that in such a scenario, the best course is complete extermination.