I want to say because of bronze, but I think it's more than just "because it's bronze". I think anything up to like high diamond, people will cry if you don't take exhaust for some reason. I really don't like exhaust, then again, I play for kills, I'm a bad support in that sense, but I'm going to take the kill if I can get it cause champions I play aren't the normal supports like soraka, alistar, and brahm and what not. I would do like Shen, Poppy, Tahm kench supports, and maybe some off meta ones.
It annoys me when someone cries about you taking a kill as a kill support who can carry. You don't see people in the LCS crying at their team support for taking a kill, and they play legit supports and go support items. I'm going carry/kill support.
I trust in myself more than I do anyone else. So I'm of course going to do what I feel is best. I seriously have seen so many people threaten to feed, or "report" if I don't go a certain summoner spell. Even when I played with high plats, and low diamonds. It's sad.
Basically ADC's are selfish kinda, and not considerate of supports.