Reviewers don't get to see the code and most don't have the time or inclination to reimplement based on what is described in the paper to check whether it tells the whole story or not. Yes, this is different from a theorem which should come with a rigorous proof. This is a great talk on the subject:

http://www.amath.washington.edu/~rjl/talks/LeVeque_CSE2011.p...