It literally has nothing to do with Japanese culture, considering that the Japanese fans were just as baffled and pissed by both the result and his reasoning. He himself derided the pairings as toxic or done out of pity (in Hinata's case). It was his dumbass attempt at covering SP and WJS's asses for them because he couldn't just say that "My editors and the animation studio in charge of the production of my manga's adaptation have been gaslighting me about the alleged popularity of this minor character that I barely care about and kept coercing me for years to replace Sakura because they have a bizarre fetish towards her, and wouldn't leave me alone to craft the story as I intended. Also, they took advantage of the fact that my father just passed so that I would be more emotionally susceptible to their needling."
I mean think about it: when SP asked kishi to do a filler arc in the war he came up with that ninja asking sakura out and him asking if the guy she likes was a great person (and you see sakura having this unsure expression). I really think he was attempting to show naruto fans that sakura loving sasuke wasn't a good thing. also he spent the rest of the war arc having sakura have a fake smile when she was around sasuke to the point where sai noticed it and on top of that had the part where karin and sakura went and saved sasuke and naruto respectively and of course the toxic behavior and rejection sasuke gave sakura