Your meaning is unclear to me. Are you asking why they don't use a man in place of a dildo? Or are you asking why date a woman with a dildo when you could just date a man?

Man in place of a dildo:
Potential emotional burden, not as convenient, man ends up more intimately involved than the woman that would normally be holding the dildo. Just inconvenient.

Dating a man instead of a woman with a dildo:
That's removing the entire emotional aspect. Women who are attracted to women are not doing so to avoid penetration. It's just the chemistry. And the addition of a dildo or other such sex toy greatly enhances the sexual experience. Liking penetration does not make you strictly heterosexual.

I really hope you mean the first meaning I thought of. The other meaning seems highly offensive to me.

because believe it or not, some women are actually lesbians.

I'm not a lesbian, I have no "hormonal" issues (aside from the normal conditions associated with perimenopause) but my husband and I use dildos and phallic vibrators because he can't be in two places at once for one. I like vaginal penetration during oral sex, he often uses his hand, but sometimes we use a phallic toy instead. Also, during DP, when his penis is in the back door, we use a dildo in the vagina for extra fun. He also likes for my to put them in my mouth for his pleasure.

I can't even believe anyone would be astounded that any women, straight or lesbian, would use sex toys. They have many uses and are a lot of fun.

It has NOTHING to do with being "sexually assaulted" nor hormone disorders, it's simply a fun thing to add to already fun sex. It's often not "instead" of a penis, it's in addition to one. Two are often better than one, and bringing a phallic sex toy into the bedroom will cause a lot less drama than bringing an other penis with an other person (and their needs) attached to it. Dildos ask for nothing and don't mind being put aside when you aren't using them.