<<save any disputes and/or arguments/resentment if the need arises.>>.
Unfortunately it doesn't - they will still take place but within the context of the power of attorney where they have the potential to cause complete stalemate wth nothing getting done because they can't agree. At least with one he can go ahead and do what is needed (paying that bill etc) and have the dispute separately
The Power of Attorney is implemented by registering it with the Office of the Public Guardian. The holder of it decides when to go ahead - but has to give notice to family members, etc, who have the right to object