I asked myself the very same question and you know what the answer is?
YES!
I have not used a social media platform since Myspace, well Xbox live and YT, but I never got into Facebook or twitter. Now that I am serious about starting up my YT channel I went ahead and got the whole suite. I made an account and updated my Twitter, Facebook, Google+, reddit, and the obvious YTTalk. I feel in the industry that is YT, these social media giants are necessary for your success. Or at the very least they will compliment any success you have on YT.