Scons uses Python more for configuration rather than the control flow. I'm sure most people think that's ok, but I find it limiting and a bit too derpy.
In fairness that's the core of the argument: a significant proportion of people that have had to maintain build tools over long periods believe they should only be configuration and not contain any control flow.
The problem with adding flow control is that establishing the dependencies without actually executing the whole process becomes next to impossible.
