Hell it does. I’ll define it in a way that denying its existence would mean that you’re totally clueless about playing League.
Elo hell is when you are teamed with people who play much worse than you, but you’re not good enough to carry them all. It’s the most frustrating thing there can be, since even if you do fine, you’ll end up with horrible results. Talk all you want about the 5/4 chance that the feeder will be on the enemy team – but this in itself is based on the assumption that there is only one of them (which is usually not the case).
Unless you’re playing on a smurf, your MMR is probably roughly representative of your skills. Which means that if you’re teamed with a bunch who are playing horrible, you simply can’t outbalance them alone against a team consisting of people of your skill level. To carry a team where all the carry roles are doing bad requires a skill level of at least a whole tier above, if not two.