The anthropic principle has nothing to do with why complex numbers are necessary for doing quantum mechanics. Complex numbers are purely abstract objects and yet are necessary for giving a proper account to the real world.
"From all of this I am forced to conclude both that mathematics is unreasonably effective and that all of the explanations I have given when added together simply are not enough to explain what I set out to account for." - Hamming
"From all of this I am forced to conclude both that mathematics is unreasonably effective and that all of the explanations I have given when added together simply are not enough to explain what I set out to account for." - Hamming