TheVanBlog gets it right on the money over whether an organization's web site is more valuable than its Facebook page. To me, it's something of a straw man argument, because I simply don't see too many businesses or other organizations deciding to cast away their web site in favor of social media, for all the reasons enumerated by TheVanBlog:
Social sites like Facebook, Twitter, and LinkedIn are perfect examples of outposts. They are extensions of your online presence.
Outposts can be taken away. They can be overrun militarily. They can be removed by the country you’re seeking diplomacy with. They can fail to generate enough business to keep going.
Your online outposts can be taken away too. Facebook can remove Pages anytime they want. Twitter could delete old tweets. LinkedIn could cease business. You never have complete control over your online outposts and you are always limited in what you can do by the sites in question.
However, some marketing campaigns can be executed wholly in social media. A lot of movie studios now seem to be creating Facebook pages rather than web sites to promote new releases, which makes perfect sense. It's far less labor intensive to create and maintain a Facebook presence than a web site that you won't be able to use again anyway.
And, depending on the level of engagement you are seeking, Facebook and other social media outlets allow you to segregate your audiences more finely than web sites alone permit. Think of a brand that is active on Facebook, like Chick-fil-A. If I'm a customer who simply wants to find out about new menu items, special promotions, etc., I really don't need to ever go to the company's web site, which can cater instead to investors, franchisees, the news media and the general public. (Though Chick-fil-A appears to have a very customer-friendly web site, no surprise given the premium they appear to place on customer service in their stores.) For customers, it's far more convenient for them to follow a Facebook group, since they are on Facebook anyway, then to take the extra, deliberate step of seeking out the web site.
TheVanBlog post also hints at reasons not to try to create a customized social networking site, something which seems to tempt many organizations, less so now that Facebook has really taken hold. My alma mater, Westminster College, has its own alumni social networking site (in addition to being on Facebook). I haven't bothered to check it out since I initially signed up. It's just one more password to remember, one more web site to visit. It's simply not worth the hassle.