I don't think this is all that useful of a quote outside of operating systems (and even there I still find it of questionable value). You really need to define

I don't think this is all that useful of a quote outside of operating systems (and even there I still find it of questionable value). You really need to define how people can use your software (at least at a high level) and receive backwards compatibility guarantees. Even in the Linux example, kernel modules do not receive compatibility guarantees because it is difficult to keep. You may need to rewrite your module depending on how it is written when upgrading the kernel. It also doesn't apply in case of security vulnerabilities and certain classes of bugs. Technically viruses can be user programs which rely on those vulnerabilities and even excluding those, there are cases where some API seems benign but later turns out to be flawed (like precise timers in the context of browsers).