It is for the airports it actually shows. I live less than 5 miles from a class D tower controlled airport that the DJI site does not show. Maybe they only show international airports witch I have 10 miles away that it does show.
I have been using the FAA app. It's overkill showing every possible airstrip and heliport but better safe than sorry.
On a side note, the airport within 5 miles from me lists a number to call if you will be flying in their controlled airspace. I've done it a couple times and they asked a couple questions but once I said i wouldn't be flying above 300' they didn't seem to concerned. one guy did ask me to keep line of sight.