I just discovered another reason why being Support is pretty damn terrible at times.
TL;DR - Your ADC leaving during the early laning phase basically puts you in a 3 v. 5 situation rather than a 4 v. 5 due to the Support's dependency on their ADC to get Gold/Experience during laning.
Look at my latest match. Our Draven fed like no tomorrow and eventually simply quit the game without saying a word. Now the problem was that this was before even a single tower had fallen; we were still in the laning phase - and as a Support, I can't do anything without a partner. They tower dived me, they obviously got more CS than me and eventually crushed two bot towers. As a result I was even more levels behind than what is traditional for a Support so when we finally got to the team-fight stage of the match, I couldn't do anything either due to lack of levels/items.
[zombie-brand-clap]