In canon, the love shield requires more than just not fighting back- the person who dies needs to have a choice between death and life, and to intend to die. (When Harry died in the Battle of Hogwarts, he didn't fight back, made the choice to die earlier, and willingly went to his death.) The love shield only applied to Harry because Lily was explicitly given the choice to step aside and live, and chose not to take it; James' death didn't create a love shield around Lily because Voldemort never gave him the option to live, and so James wasn't able to explicitly choose death.

While canon doesn't really show this, I doubt many other dark lords would have given their victims' defenders a choice between life and death. (Also, IIRC, at the end of canon, the Love Shield still wasn't widely known.)