I haven't been playing League very long and I'd be the first to admit I'm not the greatest player but, from my experience the amount of raging you get if your team does badly depends on the positions. Primarily jungling and support.

I hardly ever get raged at if I play adc, mid or top (unless your farm is extremely poor or you unintentionally feed) but why is it that support and jungling get all the rage? Does the whole game depend so much on those two roles that the rest of the team is nigh on blameless for the outcome for a loss?

I main jungle and it is the easiest to blame the jungler because he is responsible for all the lanes. Not sure about support but considering its the easiest role to play its usually the ADC's fault the lane loses.

Are you kidding, dank? The AD can only do so much. When you're playing Kog'maw with a Nunu support against Leona/Ezreal and your Nunu sits at turret while they camp bush, it's really hard to farm. The support is, early on, a big part of the lane (if not the biggest part). It's they're job to give the AD space to farm. The AD can't really do anything until late game, so if he doesn't have help from his support he's going to get destroyed.