That speaks more to what you know about other religious traditions than about Brahminical Hinduism -- there are women Christian Gnostics such as Marcelina, leaders such as Maximilla and Priscilla who were missionaries in their own right. Islamic scholars quote several women narrators of the hadith. Early Buddhism allowed women in the sangha & to train as nuns. Some like Khujjuttara contribuetd to Pali scripture like the Itivuttaka. In all religions, theological authority has been limited to men so we don't hear about them, but Brahmin-Hindusm's women are far from unique.