I've often wondered why scratching an itch feels so good and I THINK it's purpose is to break the skin to trigger the generation of H2O2 that either cleans up the reason for the itch itself or triggers the immune system to come and take care of it!
It makes perfect sense now! That has ALWAYS given me fits! I KNEW there was a reason it feels so good and I think this is, in all likelihood, that reason! FINALLY! That has bothered me my whole life as one of the curiosities that sparked my interest in alternative medicine! Since I was a kid and told to "stop scratching" every time I got a skeeter bite or anything else that felt so good to scratch!
We had a neighbor when I was a kid - Gwen. She was an older woman and a missionary who was always "off to Guam" - "The Gwen of the Guam". She could make homemade bread out of just about anything - or just about anything out of practically nothing at all and knew all sorts of things about herbs and plants. I wish I could tell her this as she agreed with me that it appeared universally so that scratching feels good and must have a purpose.