That, however, is not really an explanation, but merely a statement of what has happened. Why did one issue get a head start, and why is it being talked about in a self-reinforcing way, and the other not?

A head start is sufficient to answer the second question. It is also at least as much as an answer as 'status'. In both cases more detail is required. I am not taking a position here myself but if I wanted to find reasons for a 'head start' I would look at behvaioral trends at the time where this issue became a problem. Were people getting drunk or depriving themselves of 30 hours of sleep more often?