> I am not sure if this claim is true as well, wealth generally does stay within family lineages across cultures, generally people losing their wealth or even gaining it is an outlier. See any landed gentry in Europe, Asia

Your examples tend to prove the effect of kinship structures, which were much stronger historically across all cultures, especially outside NW Europe (where nuclear family dynamics go back millennia, which some people argue is not merely coincidental with the emergence of the Enlightenment and the Industrial Revolution).

The relevant question isn't whether wealth stickiness exists, but the magnitude of the effect and how it changes.

Kinship groups can absolutely be useful and beneficial, but as a rigid social institution it can also take on a life of its own, as for any social institution. We can't have meaningful discussions about this stuff without understanding magnitudes and context, otherwise its too easy to cynically equivocate.