Except in this case it’s like being forced to resolve disputes according to your uncle’s inexpert and biased reading of how your great-great-great-great-grandparents settles their marital spats.
Whether that's good or bad depends on your view.
If he's wrong about history, and you can show it, he's generally been willing to change his view.
As mentioned, they also definitely rely on experts for this (and are often experts themselves), and cite the expert historical analysis they rely upon.