I don't agree that they are the easiest class.
It may seem so when you get good gear and high level(also after you buy Stat Boosts).
At later levels they get even with pure Chars but before that they get severe penalties.
At lvl 15 or so they start getting even and even so you need to have better gear in comparison to pure chars to stand a chance.
And as I said, the better hybrids are those that only invest in int for low lvl buffs, and invest the rest into main stat, in this scenario I agree they are pretty much even in power.
Otherwise hybrids are almost always inferior for most part of the game.