Well, you're not totally wrong since the body does have several layers of defense to keep the bacteria in the intestine, and bad things happen when they break d

Well, you're not totally wrong since the body does have several layers of defense to keep the bacteria in the intestine, and bad things happen when they break down: https://www.pnas.org/doi/10.1073/pnas.0803124105 https://www.pnas.org/doi/10.1073/pnas.0803124105 On the other hand the immune system selects for beneficial bacteria, which take up space and nutrients so that really harmful ones can't colonize: https://sci-hub.se/10.1038/nri3535 https://sci-hub.se/10.1038/nri3535; https://www.nature.com/articles/s41586-022-05141-x https://www.nature.com/articles/s41586-022-05141-x