Here ya go educate yourself then get back to me.77 participants, not randomized, investigators not blinded. Not only that, but the study discussion states multiple times that in natural immunity the antibody counts declined significantly at 4+ months. Yeah they’re still present, but they decline significantly. How do you get them back up? You can either be vaccinated and get a booster or you can get covid again and come into contact with a variant that your body doesn’t recognize because it is specifically trained to fight the one strain you encountered 6 months ago. That’s another benefit to mRNA vaccines, they are focused solely on the spike proteins. Those don’t mutate as often.

Coronavirus Disease 2019 (COVID-19)
CDC provides credible COVID-19 health information to the U.S.
“Viruses constantly change and become more diverse. Scientists monitor these changes, including changes to the spikes on the surface of the virus. “