Hey Riot, is there a reason supports don't give shut down bounties? Or at least not shown?

I mean I love how you are showing everyone how much they are worth if they die...kinda like a "hey if you do this stupid move, this is how much you're going to give that enemy". But why we supports not worth anything? You said so yourself that kills aren't everything when you put bounties on people that had super high CS....so me working my butt off to keep my adc alive and spoon feeding him and my team kills while peeling isn't worth anything?

I mean sure...we won't have 200+ CS like our ADC or 13+ kills like our fed jungler (well lemme rephrase...we shouldn't if we doing our job) but those 35 assists should mean something at the end of the day right?

So...what's the reason for it?