Egalitarian contradiction: cultural restriction vs. Junia's early prominence

Egalitarians say Jesus didn't appoint women apostles because it wouldn't be culturally accepted. Yet many egalitarians also claim Junia was a prominent apostle before Paul — very early in the church, soon after Pentecost. How could she achieve such prominence in the same culture that supposedly prevented Jesus from appointing women? If the cultural barrier was so strong, how did Junia become more well-known than the other apostles? These two claims are difficult to reconcile.