Why? Rights are orthogonal to something being a democracy. A society could decide to have no human rights yet still make decisions democratically.

If minority rights are not maintained, then the first majority to win will change the rules/system so that the minority can never become the majority. In the extreme example, the 51% votes to eliminate the 49%. For a democracy to function minority rights and checks on the majority power are fundamental requirements.

Originally from the Dept. of State: https://www.principlesofdemocracy.org/majority

>so that the minority can never become the majority

So you are trying to say that a democracy that is unable to find a global maxima is not a functional democracy? I would disagree and say that a democracy moving towards a local maxima is still functional.