To be short, developed world lives in condition that is not natural to humans anymore. What is normal to humans, is a survival mode, hunger, every day difficulties with shelter, a lot of resources normally would go to just surviving and obtaining food. Homelessness would not have been possible in the past for example. You either find some way to survive or die. You just couldn't get food for free. Modern times you don't need to do any physical work to have plenty of food and shelter. Which means there is much more chances for LUST emotion-motivation system to become active. Which for some is expressed in overactive libido, which again could lead to various sexual deviations, mostly to various parafilias, and perhaps even to gender questioning, or lust that is related to that. That is just an assumption, I haven't find any researches regarding this topic. Or may be I have been lazy.
As in the past, when you needed to work a whole day, it did not left you much chances to have sex even with your wife, not speaking about masturbation. There was very little time allocated to LUST neural network. This might be the reason why masturbation in old times was considered harmful, as you needed time to recharge. It was felt like lost energy and time for much more practical issues in life.
What do you think about that my friends?