There’s lots of debate, particularly in USA because of the anti-online-gming laws. Basically it’s an attempt to prevent money from leaving US casinos. The argument put forward is that poker is a game of chance, and therefore not legal.
My argument is this: a single hand of poker is a game of chance. A session requires skill.
Think of it this way: Roulette or crapps are pure chance. Even if you play to lose you might still win. However, poker is a game of skill, because if you play to lose, you will lose. The converse of this is: if you play to not lose, you might not lose (not if you play to not lose you will win)