Do you think it's a requirement now for writers?
Branding is a requirement for everyone, no matter what line of work they're in. However, this is especially important for writers. Today, with the rise of digital publishing platforms such as KDP and iBooks, everyone can be a writer; everyone can get published, so to speak. But not everyone will make money.
Successful writers are those who understand branding but also have an inherent knowledge for online marketing, which is one of the most difficult and convoluted fields to master. Simply put, there are just so many moving parts and components that it can overwhelm most people.
If a writer can understand what it takes to market themselves online through things like social media, blogging, search engine optimization, and email marketing, just to name a few, they can succeed with their craft. But it's not simple and it's not straightforward by any means. In fact, it can be utterly frustrating.
So, I would say branding through social media is a requirement, but it's only a start. To really reach people out there, you need to do far more than post on a social media page. You need reach. And that takes time, something most people simply don't have or are unwilling to accept.
I've had the good fortune to understand online marketing since I've literally written over a dozen books on the subject, which you can find here:http://adbl.co/1N5w3dD
In short, it all just takes time. Start with branding on social media, yes, but don't stop there. Move into the blogosphere, work to understand SEO, build an email list (yes the money is really in the list) and do what it takes to master this unforgiving field.