My theory is because winny is derived from dht.
With dht you have a wide range of effects.
1. Hairloss
2. Prostate enlargement
3. Binds 5times stronger then test to AR
4. Cant convert to estrogen
5. Because of being dht, which can have an anti e effect, you keep water off, and by that estrogen/progestrogen.
Now progestrogen is 3 times potent then estrogen on the receptor. So maybe it actually bonds to free progestrogen molecules.
That is why masteron was such a great contest drug.
Derived from dht, no water, no estrogen, hard like a rock with no gyno.