It implies that the demographics would not be skewed naturally as a result of peoples’ free choices and preferences.
The daft (but unexamined) premise that’s at the core of regressive Left ideology is that people are equal in their talents and abilities and that therefore whenever you find an imbalance of result, reward or representation, it must necessarily be the result of “oppression” or “systemic” factors.
You don’t have to look and see whether that’s actually the case, whether there has actually been any unequal treatment or oppression, the imbalance alone is enough of a sign that oppression is in effect, so you have to mobilize, and anyone who disagrees must necessarily be evil.
The idea that men, women, various ethnicities, etc., etc., just have different preferences, abilities, talents, etc., and that those would show up even if all actual treatment of human beings by other human beings were perfectly equitable, simply does not compute.
The position is fundamentally quasi-religious, with an abstract kind of equality given an unquestioned, almost transcendental value.