I mean the guy/otaku said it best. White Day's a scam made by the chocolate/candy industry in Japan to sell more goods. Anything made by corporate propaganda is a pain in the ass at this point. It's a wonder why the west hasn't adapted to such tactics yet.
They kinda already did: just remember how Christmas and Easter are celebrated over here and just how supermarkets stock their products around those dates.
Well, that's kinda how they originally were: started tsun before transforming into dere, it simply ended up transforming from a relationship progression into an excuse for physical and emotional abuse.
For the last one I blame Ranma ½ & Love Hina, they were the ones who typeformed the tsundere into what it is known today.