It always seemed strange to me. Yuki is a good girl, and she gets so much spanking in arts.
As if the artists had romantic feelings for her, but didn't know how to show it.
So they spank her because it's their fetish.

I think many and many #spanking artists are sensual, quite and shy boys, and Yuki is their waifu, because she's probably best choise to such kind of people.

I may notice #MyLittlePony FiM has so much spanking arts for the same reason.