I don’t wholly disagree with you but, in my experience working in this arena, you’re being a bit extreme in your assessment of the “only ” viable target audience being young girls.
@karlrohde’s point about quality of fans over quantity is a great one. If your strategy for facebook is about building and nurturing a concentrated group of true fanatics and loyalists who’ll act as ambassadors for your brand, then 1000-odd people could be considered a pretty powerful “sales force” in a target audience of say, 1.5million “middle-aged decision makers”.
While I whole-heartedly agree – and often am heard raving – that facebook is not going to be a useful investment for every business, it’s important to understand that there’re more uses for facebook than the one you’ve mentioned. Opening a business page with the intention of attracting loads of people, having chatty “community building” conversation and information sharing “engagement” with them, and that engagement naturally converting to real-world sales is a pretty traditional brand-marketing model. But this tool is also incredibly useful as a customer-service portal, a CRM platform, an insight research or R&D tool, an internal comms “intra-net” alternative, or even as place to house your e-commerce store.
You’re right in saying that considering whether your target audience is active on this platform is ONE of the keys in assessing it’s usefulness but one also needs to consider of how that audience uses the site, exactly what business goal you’re trying to achieve out of the presence and then, using all that information, work out if Facebook is that place where that audience is going to be most receptive to that message and design a strategy accordingly.
We find that nine out of ten clients who come to us saying “Facebook is just for little girls” have dived onto the platform with no real research or strategy and no clear objectives to measure their results against.
I’m certainly not a blind fan-girl of Facebook as a business comms platform but I do encourage you to not throw the baby out with the bathwater. There’s a lot that’s good about the platform, and for a wider audience than “a young woman” or “an empty room”.