It still strikes me as odd how many "friends" I have that I've never met. This is despite having lived through various iterations of on-line interactivity, but we've reached a point culturally where saying "that's an internet friend" is something you can say without people thinking it's completely weird. And that is completely weird.
But it's a weird I love living in.
It is also part of what the writing community-- in being a community-- is built on. I've maintained email and social media connections with writers that I've never met or only met briefly. I've never met any of the Word Whores, despite group blogging with them. My joining up with them came about entire though on-line connection.
This isn't really a new thing, though, just because we live in the modern, internet age. Genre writers in the past would do the same thing, just the old-fashioned way. Hell, Ursula LeGuin had a long and involved relationship of correspondence with James Tiptree, Jr., without meeting face-to-face and finding out Tiptree was actually Alice Sheldon.
Of course, like with all social media elements of the writing business, you have to ask yourself, how much do I want to deal with it? Do I have to be on Facebook and Twitter and Pinterest and form bonds with other genre authors and spend half my day doing that stuff? No, not at all. But I'd be lying if I said it wasn't helpful. That interconnectivity, that mutual recognition, it has a rising tide effect. If you wonder how one book or another becomes the "buzz book", a lot of that comes from other authors. So, no, you don't have to do it, but it can be a good thing.
Plus, the writing community-- especially the genre writing community-- are cool people. Reach out to them. They will probably reach right back.