Why did it matter that Equality showed preference in the book Anthem by Ayn Rand?

Ayn Rand's philosophy, Objectivism, was a reaction against what she considered the dominant "collectivist" tendencies of 20th-century social and political thinking. Rand believed that egalitarianism--the notion that all people are equal--was wrong and was destructive of progress and man's ability to achieve. In Anthem, like other dystopian writers she presents a projection into a future, post-cataclysmic world, an extended or exaggerated version of the worst tendencies of the present. In the dystopian setting, no one is supposed to like or love any one person over others.
Equality 7's love for Liberty 5, the "Golden One," is a form of heresy against the regime. In extreme "collectivist" thinking, according to Rand, if everyone is equal, then there is no reason to prefer one woman (or man) over anyone else. Couples are selected for breeding by the regime, not through personal preference. Rand saw this type of society as a logical extension of the Communism of the Soviet Union, her native country, and of even the much milder "socialism" she regarded as gradually taking over the rest of world during the 1930's, when Anthem was first published.