I do believe that ATL (Hartsfield–Jackson Atlanta International Airport) is the busiest airport in the world, and has been so for quite some time. Dubai, indeed, is not.
Looks like it depends on how you count. Atlanta moves the most people, Chicago moves the most planes, Dubai move the most people between countries. Dubai is also #3 for the most people regardless of origin and destination which makes me think they'll remain tops for moving people internationally; all the other top airports would have a much larger proportion of domestic passengers (unless flights between Hong Kong and the rest of China don't count as domestic).
https://en.wikipedia.org/wiki/World%27s_busiest_airport
https://en.wikipedia.org/wiki/List_of_the_world%27s_busiest_...