Did Will Turner need to stab Jones's heart?
In "At World's End" Jack Sparrow is about to stab Davy Jones's heart when Davy Jones stabs Will Turner, so they have Will Turner stab Davy Jones's heart so he will live as the new ferry man of souls.
But if Jack stabbed Davy Jones's heart then Jack would be the ferry man and wouldn't Jack, as the ferry man, have the authority to free Will's soul from death?
Will would have died at sea and Jack would now be in a position to determine where Will's soul goes. Davy Jones often uses his power to force people to be his crew, and he has the power to free people from his crew; Jack could take Will's soul and free him to live.
Or is the option when you die at sea to either go to the afterlife or serve as the crew of the Flying Dutchman? Not to just go home safe and sound.