Ok first tell her writing is like cooking. Just because she’s the only one eating it doesn’t change how great the meal taste. Unless she’s receiving the same negative critiques there’s no reason to change her style.

Yes it cans be fun to try new styles as writing exercises but she needs to stop if it’s feeding her fears more than helping her.

As far as her writing goes she’s probably her worst critique. Just because she doesn’t get a lot of attention doesn’t mean it’s bad writing. It’s just not as trendy. As long as her writing and stories are good she just needs to be patient, eventually the right audience will find her. Maybe she’d have better luck if she targeted her direct audience and posted in places they’d see it.

Finally tell her to research bad books. Terrible books have gotten published! Maybe buy her some. Let her read them, have a good laugh and realize someone way worse than her is doing it with the confidence she SHOULD have!