[88e282102ae2e5b]

Not true. Optimization of chemistry is going to happen unless explicitly hindered by something else. Here, they basically crippled a protein that increases the fidelity of protein synthesis, so there's a fitness advantage to any bacteria that can increase the effectiveness of the ancestral version. It wouldn't matter if the bacteria were in a swamp or someone's intestines or a petri dish - better protein synthesis is always better.