I normally try to avoid index number theory. Don't trust me on this.
It is well understood that real GDP is a very imperfect measure of welfare. We teach that in first year macro. That is not what this post is about. What I'm worried about is whether real GDP is an imperfect measure of itself. Does it have internal validity?
If better technology enabled producers of new goods to ramp up production more quickly to meet initial demand, would that cause the measured growth rate to fall?