Ummm, I don't think it hurts. I don't know if it's that much of a myth. I think it happens. I think it happens in all businesses. But today's society is much different than it was in the '70s.
Sexual harassment is a factor.
Certainly, you'd be foolish to do it, particularly if you work for a big corporation. Seduce some girl, you know, you've got problems. Write a book. Read the confessions of a casting director , see what four Hollywood actresses have to say about the business, or meet the winners of EW's Screenplay Contest .