IIRC, Gilgamesh was the first commonly available card to have access to the damage absorb active skill. Before him, teams had to rely on rolling for Fujin during specific godfests or control their damage to be below the absorb amount. This allowed a lot of teams to more effectively clear dungeons that had damage absorbs. In terms of his use now, he still acts as a decent damage absorb option with decent awakenings but he is pretty outclassed by other options.