Someone has mentioned about start-ups and you mentioned certain parts of the world like the USA. There are some sub-cultures of developers where it’s deemed essential to walk around with your Macbook, Tweeting about anything tech related, and staying up til 2am making contributions to Mozilla’s GitHub. But it’s just a sub-culture. Do these types of people really represent “all developers” or the only people ever to get good jobs? Absolutely not. If you’ve had 4 positions within 12 years there’s no way a company would have kept you if you weren’t up to scratch. In that case, an online presence is largely meaningless.