Now that the biological dangers [of sex] are mostly gone

I know that most educated people believe that, but I've never seen a good argument for it.

At any rate I am almost sure that there are microbes causing significant amounts of death and disability (especially disability because it is a lot easier for our civilization to ignore or deny a cause of disability than to ignore a cause of deaths) that almost no one recognizes as pathogenic. And I tend to believe that for some significant fraction of these "insufficiently recognized" pathogens the more sexual partners you have, and the more likely you'll get it. (There are dozens of viral and bacterial infections -- including near a dozen at least in the herpes family -- that remain in the body and are more common in more promiscuous populations.)

In other words, there seems to be a strong selection bias whereby people tend to look only at the pathogens that are recognized as pathogens by, e.g., doctors.

It might be however that these biological dangers from less-recognized sexually-transmitted pathogens are concentrated in people who are old or already sick.

Any professional biologists or medical researchers wish to chime in?