Because we like to think about solutions to the inherent problem at hand, and not a solution to a single situation.
We’ve met about this feature multiple times and spent unknown hours discussing it… WoL provides such a bad user experience, and we are trying to fix that core bad experience in a way that doesn’t have us building a complicated WoL system.
We can solve it nicely in some simple cases (the one you state), but it’s unclear to me if that is the common case.
We’ll keep on thinking about something, but in the meanwhile, use a 3rd party WoL app that solves this problem for all use cases. Sorry guys! I know it’s not the answer you want to hear, but this is what it takes to make good software.