I'm don't mean to speak for Bobby (and I'm not ;>) - But by self regulating I don't think he meant teams only bring "X" number of engines to an IHRA race. More likely some teams 'self regulate' by using parts (floaters, belts, pistons, rods, tires etc.) that some NHRA teams would throw out. (Thus the market for 'gently' used heads, crank shafts, blocks).
Plus since those parts maybe closer to the end of their life cycle - teams aren't willing to push them as hard with the end result leaving rods hanging out everywhere.
That's just my take - and not necessarily the strategy of any team (NHRA or IHRA) in particular.