Comment by kallyaleksiev

feels like there's two slightly distinct phenomena that are interesting to point out -- implicit (or explicit) dependency on something that is actually true vs dependency on something that is not true

in the latter case the client forms a dependency on observed service behaviour based on an incorrect assumption of a contract -- i.e. as with the Google Chubby service story -- so they end up getting burned when the server does not satisfy that (of course it's the developer's responsibility to prevent them from forming the dependency in the first place)

the former is when clients form dependencies over assumptions that are actually correct but have not been intended to be observable, e.g. using some sort of nice library or data structure internally, then users starting to depend on that performance, making it hard for you to change the implementation