bullshit, the function of the pectoralis is to pull the arms down and across the body. decline is best, followed by flat, and incline activates the pecs the least of all three.
incline is beneficial for thickening up the upper chest but building your workout around it is stupid.
I would say what is best is very individual, like so many other things. If that wasn't the case you wouldn't have so many people saying different things.
Arnold liked flat (and incline), yates likes small decline or small incline, ronnie does flat, incline, decline, levrone flat + incline , some don't like barbells and prefer to do dumbells etc etc