Originally Posted by
clarkef
To the extent that we are discussing the armrest that abuts the window, the passenger's size really isn't relevant.
The OP discussed armrests in general ("Can someone explain why some of the aisle/window facing armrests on AE flights have a metal plate ..."). The question I answered was not specific to armrests on the window side. Obviously, passenger size isn't a factor there, but the premise of this comment ("To the extent that ...") is wrong: we're not.