Quote---...boost is just a measurement of restriction.
The measurement is just a number used for comparison purposes, and doesn't take into account where the restriction is. In a particularly wide-open intake tract, the resistance (restriction) might well be the piston crown.
But we are talking about what's happening---in the vernacular, we're crammin' more air into the cylinder while the valve is open. If there were no other factors to be considered, the more the hole is open, the better. But particularly, considering the 'demand' component we have to deal with---the fact that unless we are 'in boost' we have, in effect, an NA engine, all the other factors come back into play.
Let's not forget that it's 'more air' that we're looking for, and let's not get hung up on how we measure it.
KS