I believe the same is true of "best practice" today: game studios aren't actually behind the curve, you just don't hear much about how things are progressing on this end because most of the conference talks aren't about broad concerns like testing, they're about the myriad specialities of the field.

And there absolutely is a legacy-code thing that hinders AAA in many cases. When the engine is old, that's good, because it's shipped something, but it's bad, because it's using older practices and Things Have Moved On.