I agree with the notion that elo is a real thing, but only because I played in 800 elo for the beginning of S2 and got up to mid/upper 1400 elo in S3. I can speak from experience that the people who play in lower than 1k elo make the game harder.
They rage more, and are generally not as experienced as the 1200 crew, so winning games becomes a much greater challenge.

However, I should state that elo hell isn't a place where you cannot possibly win games. That's not true, you can win games. I got out of 800 elo to 1360 at the end of season 2 by playing support. So yeah...
Elo hell just means that a majority of the players you encounter will either be ragers or they will be inexperienced, so winning the game is harder. Would I say it's impossible to get out? No.