compiling as root?

Linux people generally recommend that you do not compile source code with a user that has superuser privileges, which I assume is a guard against possibly malicious commands that may be in the compile scripts. When I install packages with macports (sudo port install xyz) they're compiled by the root user. I assume that the developers have thought about this and decided that it is not a security problem. But I am curious, is it ok or not ok to compile source code as root? cheers