When you go to the hardware store and ask for something to pound nails, they give it to you. When you ask people what they use to pound nails, they say they use this. When you're hired to pound nails, they often insist that you pound nails with this. 99.9% of the people who use this on a regular basis use it exclusively to pound nails.
Given that context, it makes little sense to say, that's unfair, it's really a screwdriver.
My point is that not only do roughly all the users use it that way, but the make agrees with that usage.
At some point you just have to say, this hammer, while apparently designed as a screwdriver, is clearly labeled, sold, purchased, and used as a hammer and is not very good at it.
Given that context, it makes little sense to say, that's unfair, it's really a screwdriver.