One possible factor I don’t see mentioned so far: A structural bias for action over inaction. If the current design happened to be perfect, the chance of making it worse soon would be nearly 100%, because they will inevitably change something.
This is complementary to “mean reversion” as an explanation—that explains why changes make things worse, whereas bias-towards-action explains why they can’t resist making changes despite this. This may be due to the drive for promotions and good performance reviews; it’s hard to reward employees correctly for their actions, but it’s damn near impossible to reward them correctly for inaction. To explain why Google keeps launching products and then abandoning them, many cynical Internet commentators point to the need for employees to launch things to get promoted. Other people dispute this, but frankly it matches my impressions from when I worked there 15 years ago. It seems to me that the cycle of pointless and damaging redesigns has the same driving force.
This paper seems like an interesting counterpoint: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5421578/
Estimates of Ethanol Exposure in Children from Food not Labeled as Alcohol-Containing
They find that:
This is estimated ethanol exposure just from eating and drinking regular non-alcoholic food and beverages. A dose of 10mg/kg of ethanol is hundreds of milligrams total, per day—more than an order of magnitude higher than the highest estimate discussed here for the bacteria.
(I will note that I had difficulty verifying any of this; there are lots of news stories on this topic, but they are all fairly fluffy, and link back to the same single study.)