Lol, I think this really shows how the stigma of diapers is ingrained at such a young age (around the age of potty training, presumably!) I can't imagine any parent is trying to do this, it's just the way it is when you want to encourage your little pee and poop machine to use the potty instead, then the entire society ends up reflecting this subconscious and irrational idea with many never needing to confront it.
Diapers are for babies, pee and poop are gross, diapers hold pee and put poop, therefore diapers are gross. Tampons and pads are gross too, but more acceptable because you can't deny that half of all adults need and can't avoid them, just don't discuss it.
I got over my irrational uncomfortableness with the word diaper around the time I accepted my DL side. Someone else said it, I don't want to wear incontinence briefs or pads, I need to wear diapers. There's some power in taking ownership of a word vs. being irrationally shy of it. Today I no longer cringe when saying it, nor give it a second thought.
Also of note is Adam from Northshore trying to do his part at normalizing the use of the word diaper instead of euphemisms for the products he sells.