The caveats (perhaps not mentioned in the article) are: - Perhaps you have many metrics you need to track/analyze (CTR, conversion, rates on different metrics), so you can't strictly do bandit! - As someone mentioned below, sometimes the situation is dynamic (so having evenly sized groups helps with capturing this effect) - Maybe some other ones I can't think of?
But you can imagine this kind of auto-testing being useful... imagine AI continually pushes new variants, and it just continually learns which one is the best