One reason might be that Accutane users are younger and 50% female. If someone has their sexual function destroyed before it ever really started because they are taking the drug during adolescence and puberty, then they might not know they have dysfunction caused by a drug. Women are able to have sex even without libido whereas men cannot. Libido and arousal are more critical to male sexual function than they are to female sexual function. Maybe a lot more women and children would realize they have been affected by the drug if they learned about the effects it can have.
The average propecia user might have been getting erections and having sex for 20 years before getting shut down by the drug. So its crystal clear for him what the drug did. Thats not the case with accutane.