People learn a certain behaviour and stick to it. The advantage is that they do not need to consciously remember an action, but can act unconsciously, thus reducing cognitive strain.
Now what happens when a well-known UI is changed? People would need to adapt, but will stick to their learned behaviour at first. Like Little Big Details shows, Chrome moved the search field on new tabs but still allows to enter search terms when users tap on the empty area where the field was before.
It looks like an Easter Egg, but is actually a well-designed UI.