I wrote a sentence like the following one in another site.

"He" as a gender-neutral pronoun had been universally used for centuries before the women's liberation movement in the 1960s.

It was edited by an apparently native English speaker as follows:

"He" as a gender-neutral pronoun was universally used for centuries before the women's liberation movement of the 1960s.

I don't understand why "had been" should be replaced by "was".