Some random thoughts:
- Everywhere says the pressure of an active fermentation keeps oxygen and infections from getting in during brewing, but why wouldn't the carbonation pressure also prevent oxidation in plastic PET bottles? Is there any evidence at all that carbonated PET bottles get oxygenated?
- The environment is full of microorganisms. Without laboratory grade control, every single beer is definitely heavily infected. Before the advent of the modern yeast industry, the entire process would have been incredibly biologically diverse. Yet, beer has been with us since prehistoric times and all around the world in every environment. So, is it possible that obsessive sanitation is all pointless and the only true problem is exposure to oxygen?