I agree, but that term is used in part to make kelp products more accessible to consumers who haven’t had it before. No one wants to eat “algae”.

Sea lettuce, Irish moss, nori - those names all allude to plants. In part because we thought they actually were plants/vegetables, but I think the names haven’t been supplanted (pun intended) by the industry because many consumers without a science background would still assume they are plants and be more likely to try them.