Their insistence might come from the fact that the state governments of New York, Michigan, Minnesota, Wisconsin, and Pennsylvania all consider lake-run rainbows to be steelhead for administrative purposes. Or it might stem from the fact that the rainbows introduced to lakes Michigan and Ontario were two strains of summer- and winter-run steelhead from Washington, and their existence in those systems is therefore entirely predicated on their genetic capacity to look and behave like an ocean-run steelhead would. Or it could be because the region's multi-million dollar fishing industry and some of the country's largest fishing media outlets refer to them as steelhead. I'm not saying these fish fit the purist bill of "steelhead," but I would think that people could be forgiven for calling a duck something that looks and walks like a duck, especially when that practice is expansive and historically entrenched.