The threshold for this effect is
font-weight: 500. At that weight,
font-family: "Futura"will indeed produce Futura; at
font-weight: 501and above,
font-family: "Futura"will actually produce Futura Condensed Extra Bold.
By the way, at any weight,
font-family: "Futura Condensed Extra Bold"will produce Times New Roman. I'm not sure why; the charitable explanation is ignorance.