Promoters have a comfort zone, and breaking out of it isn't easy. Adopting novel technology and trying new things has a price, but with some research, promoters can increase their effectiveness and build long-term success.
Many promoters rely on low-return activities like handbills and posters, which have their place but are simply not enough in today's oversaturated entertainment landscape. There's too much competition for attention (movies, sporting events, TV shows, parties), and the response rate is low. Social networks have become the new low-hanging fruit, but they, too, are ineffective if your reach doesn't grow.
Posters are passive, flyers are thrown away and people ignore Facebook invites. While I know some promoters do have success with these, it's not because of the method, but the brands they've established. Promoters must become brands trusted sources of quality that both venues and patrons respond to favorably. By adopting new ways to promote quality content and increase loyalty among your patrons, you stand to build a stronger brand than the "paper-based" promoter.