Newspapers and magazines have the same basic idea and have been successful for a long time. The internet just happens to be a faster and more mailing list convenient means of having information delivered to you. In order to become successful on the internet today, it is common sense to realize that visibility or traffic on the Internet is one of the basic keys to successful marketing.
This has become the real benefit to owning or creating a site like this. You can market to the members any time you desire. Have an idea for mailing list a new widget you think would benefit your email base... send them an email. Using Email marketing to the members of a site like this is absolutely unlimited and doesn't cost anything to generate.
While the content and marketing of your site is of vital importance, you absolutely must have an air-tight program in order to function as an online business. Marketers who set up huge membership sites usually have an email list that numbers mailing list in the thousands and a brand that many recognize as 'expert' in that field. For example, you could create this and use it to virrally grow a huge email list for a product launch that you are in the process of creating.