I've heard (I forget which of two sources it was so I can't cite) that per anthropological theory, the Tasmanians had taken not a retrograde, but an alternative, approach - that there are two branches humans have taken in regard of technology.

One is to have a maximal technology base, growing as new ideas are learned and maintained down the generations by apprenticeship and later by writing. Even at the flints-and-shells stage this requires specialism to get things done expertly.

The other is to have a minimal technology base, one kind of pot, one kind of weapon, windbreaks instead of fire, and all made out of things that can be expediently rustled up from common materials when needed and casually discarded when not, and which can be taught without effort and without specialism. It means that the species can be scattered down to the least grouping, and lose nothing. It means the individual is complete, alone and naked. They can drop everything and recreate it afresh at need.

The Tasmanians (and to a lesser extent, the aboriginal Australians) took that path. It wasn't some sort of massive technology fail. It was a different way to be successful.