How much of the Dead Ladies Club can be explained by GRRM possibly making a deliberate point about women’s lives and contributions being minimized or outright erased in a deeply sexist society such as Westeros and how much is simply incompleteness/author oversight or error?

I don’t like trying to read people’s minds with so little evidence to go on.

However, if it was GRRM’s intent to make “a deliberate point about women’s lives and contributions being minimized or outright erased in a deeply sexist society,” it hasn’t really worked, compared to other of his efforts to make such critiques (think Cersei’s walk of shame).