が in ゆえに or んがため; が > の shift?


I am well aware that が and の are interchangeable in cases like
[this](https://japanese.stackexchange.com/questions/12825/how-does-
the-%E3%81%AE-work-
in-%E6%97%A5%E6%9C%AC%E4%BA%BA%E3%81%AE%E7%9F%A5%E3%82%89%E3%81%AA%E3%81%84%E6%97%A5%E6%9C%AC%E8%AA%9E)
where there is a "subordinate clause" (forgive my imprecise language).
However, as I was working through my N1 grammar reviews, I noticed that が is
used in situations (other than the "subordinate clause" pattern) where の could
have worked just as fine.

For example,

> 経済的にあまり恵まれていない地位 **が** ゆえに十分な教育を受けられない人がいる。

I think I read somewhere that there is a shift somewhere in history that
caused の to take on some of が's functions, but I am not quite sure. Can anyone
shed light or share reference on how this happened?

