> It may read like harmful advice now, but I can imagine that "don't fuck too much" might have been meant well back then
It may not be "politically correct" as we've got a culture obsessed with promiscuity and decadence (it seems), but it's definitely not harmful advice.
I can't think of a downside to reducing sexual partners to a minimum. On the other hand, there's a lot of research that promiscuity/increased number of sexual partners are causing a lot of problems. I'll share a few.
It awfully feels like we are rediscovering some things that many, if not all civilizations knew before us.
A book that touches upon this topic is "The Fate of Empires". There's a section about causality between decadence and societal collapse, and the author is of the opinion (based on his research) that civilizations go through very similar steps.
Once a society gets to be "wealthy" enough, sexual perversion and promiscuity is on the rise, fertility drops, shortly followed by general decadence and apathy. Inevitable, it leads to a collapse (or being occupied by a culture that still keeps doing what the (now) decadent society used to do).
In a way, it's an organism. That's how I like to think about it.
Some societies collapse over a span of period, so it's not instantaneous. Therefore, probably, it's difficult to tell that it is happening. The average was found to be around 250 years.
[0] https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1741-3737....
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3752789/
[2] https://www.amazon.co.uk/Fate-Empires-Search-Survival/dp/B00...