What one gains by viewing humans as machines is a framework from which to shock others. Migdley writes:
The reductive party...is positively pleased to sound harsh, strident and paradoxical, since it views these qualities as marks of realism. Its basic project is to unite humans to the rest of the biosphere by following Procrustes, by paring all human peculiarities down to a size which fits easily into the supposedly universal evolutionary pattern. (The Ethical Primate, page 5)
These views provide a justification of Social Darwinism which has its origin in Hobbes' view of self-interest.
I don't think that the current Social Darwinists really see themselves as machines as much as they like to see everyone else as machines. Their self-interest would be to position themselves as that machine that knows it is a machine. Maybe that makes them an upper class machine? However, if they really saw themselves as machines they wouldn't waste their time trying to convince anyone about anything. What's the point of doing that if we are just machines?