Actually - knowledge of one's own body and what works sexually for oneself is as important to good sex as knowledge of one's partner's body or of bodies similar to that of one's partner.
If virginity = intact hymen then men are incapable of being either virgins or indeed non-virgins - and yet many, many men and women always refer to the concept of virginity in relation to men. Also, many female humans who've never had any sexual contact of any kind, including masturbation, would not be virgins because a hymen can be broken in a non-sexual situation (many girls who horseback ride from a young age have ruptured hymens, any nasty fall jarring that area can rupture the hymen).
Clearly it is utter shite to say these girls / women aren't virgins.
Virgin, in the broader sense, means untouched - virgin territory, virgin snow, virgin canvas. A woman who has had sex with women is not untouched.
Sex does not have to include a penis, a phallus or penetration of any kind.
Whether or not one individual chooses to recognise the sexual experiences of another as 'valid' or not is completely immaterial.