User blog comment:Big Lupu/The Curse of the Supports/@comment-6385806-20130419191459/@comment-3308937-20130420091807

It doesn't mean a role is better, it means that, given the circumstances (a late game teamfight), that role is worth more alive in the fight than another. I'd rather have a late-game ADC alive over anyone else on the team, does that mean that ADCs are the best role in the game? No, it does not, it just means that in a late-game teamfight they are more valuable to the success of the fight than any other champion.

The support is supporting their team by absorbing damage that the ADC could have taken and by doing that provide an opportunity to the ADC to keep on dealing damage. Saying the support is just dying is the wrong way to look at it. The support is redirecting the enemy's damage and spells onto themselves to keep their team alive and healthy, they're sacrificing their resources (in this case health) as a way to preserve or enhance their team's resources. It's not that different than casting a shield or a heal, which uses mana as a resource instead of health, on an ally to preserve or enhance their resources.