Well, you can buy 3 AAA games for that money, which, depending on which games, will likely provide more entertainment and value than the Obby rank.Nope, you chose to buy it or not. And since you get what they promise when you buy the rank it's not a scam.
And about OP:
I can't understand why people say the games in op are longer... I vote op in every single game I play, because it's faster and it avoids campers. With 20 iron you can get enough gear to break 1-3 eggs, and even enough to eliminate the players, while in normal, you have to have more iron » more waiting time » less action...
Well, if both sides decide to use that decreased waiting time to get armor faster, then you will both be stuck in a stalemate unless one side does something really, really stupid. But from there both sides get full diamond and most likely enderpearls. If you also have full diamond and the 64 diamond sword, you are fine, if not:
Yer just ded.