One of
( Here be lengthy pseudo-scholarly fandom rambling. Feel free to skip if you couldn't care less. )
In short: We're looking at a colourful mix of influences and historical inspirations. If a "Middle-Earth = Middle Ages" fanon genuinely exists, it's bullshit. Or, more gently put, it has no basis in either canon nor logic. Of course, everyone is free to depict their personal version of the Elves and Gondorians and Hobbits and what-have-yous in whatever terms they desire. But they can't expect everyone to subscribe to the same set of rules, and shouldn't.
Now I crave me some steampunk Valinor fanfic. Anyone seen such a thing recently? Link me? (Please do, before I have to write it myself. >_>)