The women here are rachmanus cases. The problem here is clearly a cult, not a logical outgrowth of tzniyus. This cult fulfills some psychological need these women have.
In modern society television has spread anorexia internationally. A psychologically balanced and emotionally sound, girl is much less likely to become anorexic just from watching thin women.
In meah shearim there is no TV. So these women with underlying psychological problems turn to something that is closer to home: namely an extremist person who can satisfy their unhealthy psychological needs.