Traditional Chinese medicine advises against too much ejaculation. There are recommended frequencies depending on age and state of health. Semen is said to contain 'essence'. Chronic loss of essence depletes the energy of the constitution and has all kinds of knock-on effects on the body. So the TCM point of view fits with some people's experience here. Even when I was using porn, I didn't ejaculate very often (compared to the average bloke I guess) and I have better skin than a lot of people my age (though there are of course a lot of other factors - food, exercise, not smoking and so on).
Ditto the dick shrinking. Before I started NoFap this time (I was on Through the Flame a few years ago), it felt like it was disconnected from my body, like after a cold bike ride when I have to check it hasn't fallen off. Now it is starting to warm up again and sometimes it hangs down rather than retracting to a shrivelled stump (sorry for the grim details). I haven't suffered from ED but I'd say my erections have felt less full and strong during the past year, as if the blood doesn't fully penetrate into my cock. Since I started to abstain, I can feel warmth going into my balls during meditation.
The assymetry thing some people mention, would that be because of the posture during PM as well as loss of essence? My shoulders used to tighten forwards when I was watching porn. This is a ridiculous thing to admit, but I used to change hands to even up the strain... Yet another thing that made the habit so totally repulsive.