The Stucco Keratosis you have imaged here is EXACTLY what mine looks like; no need for me to include my pics because they'd be identical.
I've never used drugs, never smoked, and was very athletic. My diet, compared to most other people, was very good. I had been a lacto-ovo vegetarian for a short time, but now just do everything organic and in moderation.
This condition seemed to have crept into my life right AFTER I had a very stressful period at around age 37. It started near the end of the summer of 1987 with just a couple of tiny dried raised spots and now, after 25 years, it has gone up to the creases of my groin and miraculously stopped, right there.
I've tried the shaving them down routine, but that is only cosmetic and does nothing to combat the problem. You seem to have done much of the same research on the issue as I have only another site I reviewed (Wikipedia) had mentioned the used of glycolic acid topical treatment.
The glycolic acid physicians grade, it appears, starts at a pH of 0.6, which is extremely acidic, and runs up to a more cosmetic application of 2.5 pH. I haven't tried it yet, but with the thousands of these little buggers that I have and some of them getting a little too close to the jewels, I'm a little reluctant to use it all over.
I did run across a few articles a few years back that DID state that it was an HPV, possibly of three different types. One of those that I happen to recall was type 23b, but I have no other other information about it or the others at this time. Its buried deep in the bowels of my Bookmarks section.