Why? Why does everyone 'need' a personal website? Reasons presented in the article are why you would want one, and they break down to bragging.
I'd like to see a discussion over whether a personal website is a better investment of one's time (and money?) than a LinkedIn profile on balance (maybe for certain people). It may be controversial, but I imagine there are good points on both sides (more detailed insight about exposure from google analytics on someone's and better export affordances with personal sites; a real network and infrastructure on LinkedIn's side).