I think what he means is a certain "frestyle potential" of those activities, basically creating complexity based on a limited set of rules, rules you make up yo

I think what he means is a certain "frestyle potential" of those activities, basically creating complexity based on a limited set of rules, rules you make up yourself, which then work in tandem with the procedural aspects of the activity and determine the limits of complexity. While this is true for many real world activities, Lisp seems to be an outlier there, because most other programming languages don't allow you to change the underlying rules.