Hmm but this was an allergen, where having more white blood cells at the site isn't beneficiary. If it was bacteria or a parasite, then the story might be very different.
"That being said, because mast cells are also involved in innate immunity, the researchers wondered if scratching's role in activating them conveys some kind of infection-fighting benefit.
Sure enough, they found that scratching did in fact reduce the amount of Staphylococcus aureus on the skin. S. aureus is the most common bacteria involved in skin infections and is most famously responsible for staph infections.
Still, in the research team's opinion, the reduction in this bacteria from scratching doesn't outweigh the way in which the behavior worsens the area around an itch."This statement is carrying a lot of weight, and isn't properly justified.
The authors say the reason the skin gets so inflamed is the presence of all the immune cells. They then go on to say that the immune cells seem to kill potentially harmful bacteria in the area.
What is the reason they say that the body's response is problematic?
It sounds a bit like saying that the fact that our upper arms become sore after an vaccination (also immune-response related) outweighs the benefits that having vaccination has.
- Contaminating the site
- Spreading whatever is causing the initial wound
- Weakening the skin barrier and allowing whatever contaminant/infection to penetrate deeper/spread below the skin.
TLDR: They show a potential benefit of scratching (which may explain why it evolved in the first place) but suggest it doesn't outweigh all of the established harms.