The question of how any biological impulse operates within the economy Debord describes is an obscure and not a straightforward one. I'd say our human (i.e paychological) impulses come to the front. That is to say, the mind as developed in modern capitalist society obscures the biological link if any to signalling attractiveness.

In the context of signalling theory, this comes down to honest vs. dishonest signalling.

Maybe better to read “appearing” as “appearing to have”. Even if you limit yourself to talking about sexual selection, the argument is that modern industrial capitalism has brought about a sea change in how that functions.

Whether you stick with evolutionary biology and say that regardless the end goal is to get laid is irrelevant; he argues the mechanism has changed in important ways.

Humans used to consider ourselves to be more than just products of our biology.