In many ways, we’re better off now: publishing online is far easier, less time-consuming, and more accessible than it has ever been, which has brought content, voices, and consumers online that wouldn’t have been otherwise.
But all of these proprietary networks that want to own and hold in your content are reversing much of the web’s progress in some other areas, such as the durability and quality of online identity.
If you care about your online presence, you must own it. I do, and that’s why my email address has always been at my own domain, not the domain of any employer or webmail service.
http://www.marco.org/2011/07/11/own-your-identity