You can jerk off and have sex with a woman and still have ED. There are varying degrees of ED:
0 being you have no ED and can get rock hard erections, spontaneous erections, instant erections, and can perform. 10 being you can't get any erections in any scenario not even morning wood.
I'm saying some men who take finasteride lose SOME of their erection prowess. Maybe it doesn't stay hard as long or needs more stimulation to maintain its erect state. I'm saying I loss morning wood, went soft on occassion even during intercourse, and always had to touch it in order to get hard. The wee I quit finasteride after taking it for 8.5 years I started getting rock hard morning wood, spontaneous erections, and never went soft during intercorse and it stayed hard for minutes on its own without needing to be touched. Huge difference. Could I still get erections sure. Could I still have sex and ejaculate sure. Did I have ED. YES