It's not that simple. Suppose you ran an A/B test like you say. User 1 goes to website, it's site A. Dislikes it. Nothing happens. User 2 goes to website, it

It's not that simple. Suppose you ran an A/B test like you say. User 1 goes to website, it's site A. Dislikes it. Nothing happens. User 2 goes to website, it's site B. Loves it. Tells friends. Now how do you track that 'virality' element? How do you know if User 1 was the cause of increase traffic, or user 2? How do you know if I tell my friend "Hey checkout bing it has this awesome blue color", and how do you know if I was an A user or a B user? I think there's just too many untrackable elements in a case like this. And in any case, the story still sounds like there was no A/B testing involved. Just "we changed a color", and later, stuff happened.