I take issue with the wording "natural usage", as there is nothing that is "natural" about keyboards. At least not in the sense that someone would "naturally"

I take issue with the wording "natural usage", as there is nothing that is "natural" about keyboards. At least not in the sense that someone would "naturally" rather grab things with their hands rather than their feet. This is why to me neither ctrl-f nor PgDn are natural, and anyone can choose one or the other. Ultimately they were both created by someone who saw the need to have a shortcut to move one entire page down.