You may think this situation is still irrational, that the other person is being irrational. But again, there are many life situations out there. Perhaps they have lived in situations where they had to fight for what they needed. Perhaps they lived with an earner who would spend their money on drugs if it wasn't taken away, and yet if the non-earner saved it up themselves, the earner would find it and spend it.
The supposedly rational thing may depend on everyone around you to also be rational, and everyone around them, etc. And given that we are human, and humans are not fully rational...
I wouldn't say this is a better strategy, but you can definitely min/max this even if your income is not stable by extrapolating out your expected income and expected witholding a few times a year and adjusting your W-4 based on your calculations.
