AA officially stopped doing it in 2016, but I found informally that they kept doing it for many years after that date if you got the right check-in agent. These days its 100% no in practice.Must have changed since I flew or is it a DFW thing? Certainly AUS-LAX luggage was checked through, in fact AUS-LAX-SYD-WLG, all the way.
Edit: As PF said, I'm talking about separate tickets, which are becoming increasingly common as AA restricts more and more award space to partners.