Not discarded, just abandoned. The data collected by anthros in grass skirts is static. What extant hunter gatherers tell us that they eat just is. They might even be able to tell us what they have eaten in the past but no longer eat. But there's not much more data to be collected, and the picture is still incomplete. So the paleo* fields are taking over. Paleobotany, paleoecology, and basic questions otherwise not answered by marginalized peoples in their marginalized environments.

There is only so much mongongo nuts can tell you about the evolution of humans. There is much knowledge to be gained from actually looking at what lived alongside Homo as it evolved.