help with term

could someone please explain what is meant when they say the Cubic Inches will eat up the cam. I am stroking a 360 to a 408. So many people I talk to will say the cam will act a little smaller because of the motor being stroked. I understand engines, but need a little clarification on how exactly that is meant. I mean a .575 lift cam will still have a .575 lift in a stroker. so how does it eat it up?
Thanks for the explanation in advance
Rod