Used to be called the Crow-ThrowFlick handballs should be illegal.
Players should be told that they will be losing the benefit of the doubt when it comes to umpire interpretation of correct handballs = If it doesn't look like a classic handball and you cannot be certain it was a handball then the umpire should pay a free kick for incorrect disposal.
This will create some injustices at first, but it will stamp out incorrect handball technique and eradicate the flick handball which has become an epidemic. (I mean the quick flick of the ball which is both hands moving with the ball in the same direction at the same speed (basically a throw) and not the ball being propelled by the fist).
Once the current trend changes the umpires can go back to being less strict.