Basically yes.
The initial timing of a pre-emisions or non-CAP engine provides good power, and idles smooth and strong.
The same engine with a CAP package used much less initial advance. The mechanical advance in the distributor makes up for that above idle rpm.
Pick an engine in the mid-60s that had both a non-emissions and an emissions reduction package on it and compare the inital timing and rpm. Then look at the mechanical advance of in the distributor of each. I've posted a number of these in graph form. Here's one