Probably depends on the type of hormones they take & in what doses. Some types of estrogen act differently than others. I.E. Some have transwomen grow boobs, others don't, some make them go infertile, others don't, some make them produce less cum, others don't, some make their dicks less likely or harder to get hard while others don't. And then there's how their bodies react to said estrogen. The main reason for multiple types of estrogen is because how your body may react to it may be different than other people's. Ergo, some transwomen's dicks stop working while others' don't.