Iterating over lists: why so limited?

[Mark R. Lindsey]

The cfengine tutorial says that `for security reasons' iterating over
lists is only allowed in a few places. What are the security 
reasons? I'm skeptical.

I have an application where I'd like to iterate over a list of
IP addresses when building firewall-type filters. The list would
be defined as a set of IP addresses, and I'd like to use an editfiles
action to create a filter rule for each of those hosts. Doing it 
with the shell is obviously quite messy.