On a recent coast-to-coast flight connecting in DFW, AA changed our arrival and departure gates at DFW twice each during the course of my inbound flight. I realize that last-minute operational issues arise, but in my experience, AA changes gates much more frequently, and closer to departure, than UA or DL.
If that's AA's approach, then why announce a gate -- at least at a hub -- more than a couple hours in advance? If passengers (especially those with paper boarding passes) don't check for updates, they may rely on stale info.
European carriers often don't announce gates until just over an hour before departure, so it's feasible.
EDIT: I should add the third and final change of my connecting gate in the four hours before departure was from C to A, announced on the app 71 minutes before departure.
I would be more willing to trust AA's distinct approach if its ops were vastly better than UA's and DL's.