You are certainly correct about promiscuity playing a significant role in the spread of STDs, but it is a pre-medieval notion to impute intentionality to Nature or God or Evolution to punish the promiscuous with those afflictions. At it s core, you way of thinking is superstition. 

The fundamental problem with you line of thought, IMHO, is consistency. If ST diseases are Nature/God's punishment, then all diseases warrant the same treatment. May I invite you read the Book of Job. Job's adversaries insist that human misfortunes, including disease, are irrefutable proof that Job is being punished for his sin. Job takes the opposite view, and in the end, Yahweh himself rejects those primitive convictions of Job's adversaries. Although we don't have reliable dating for the Job, it would certainly be before 400 BC. That is what I meant when I describe you line of thought as pre-medieval. 

So, not only the episcopal magisterium disagree with you, so to does scripture. Thin ice for sure!