I never say anything about d being even. Rather, as soon as d > 0, x{d} is even, so "almost all" x{d} are even. As you vary x and d, you cover all integers exactly once, so from this perspective, "almost all" integers are even.
My point is that this is very similar to how elliptic curves are being counted here.
My point is that this is very similar to how elliptic curves are being counted here.