What that actually means is that if you change a command so that it runs a totally different program the script would break, which is equally true in a stringly-typed world.
Though in the stringly-typed world, it's when the format changes from:
A B C
to:
A B D C
Or some other such thing. Your string processing code (perl, sed, sort, uniq, etc.) expects certain things that have now changed because <reasons> (which may be totally reasonable or unreasonable).
