I think you missed part of the point of what the article was trying to say - or rather, what they hoped to do with this strict python. One of those things being some form of hot code loading. A snapshot of the state can't be incrementally rebuilt - it's very much all or nothing; whereas if we know or modules are side effect free, or at least some useful part of module loading is, we could cache that part and get faster start up times on incremental changes.