From each according to his ability, to each according to his needs

This phrase is the basis for enforcing an equal society, not an excuse to establish a different type of economic caste system.

Doctors will still exist without our society disproportionately rewarding that behavor.

Engineers will still exist without our society disproportionately rewarding that behavor.

Sanitation workers will still exist without our society disproportionately rewarding that behavor.

There is no situation where a caste system results in a more equal society than just equal wealth distribution.