I have to criticize this claim that YOU A-B-S-O-L-U-T-E-L-Y NEED A PERSONAL WEBSITE AS A SCIENTIST, because it’s wrong. You don’t.
So, you need a personal website. Why? Because you need to stand out. Because you need to have a consistent presence when you change employers. Because the university profile isn’t sufficiently yours, and an academic networking site is too closed off. Because it gives you the opportunity to learn to communicate to a wide variety of audiences, including your peers.
There’s empirical evidence against this claim: there are many scientists far more prominent than I am who don’t have a website (and some who do), and there are scientists who are less prominent than I am who do (and some who don’t). Why, it’s almost as if having a website is irrelevant to success in science.
I’m on a university committee engaged in a job search. I’m a web nerd, and I didn’t do a single search to see if any of our candidates have a website. It wouldn’t matter if they do. My fellow committee members would look at me funny if I tried to suggest that Candidate X was particularly enticing because they had a website. We look at their CV, teaching statement, research plans, and recommendations…not what they say about themselves on the web. Get real: maintaining a web site takes time and effort, and we’d rather see that potential colleagues are doing good work in the classroom and the lab. It’s a matter of priorities, and “personal website” is very low on the list.
That said, however, a web presence is important for public outreach and communication. If public engagement is one of the criteria for a science position, not having some sort of actively maintained web presence is definitely a failure. There aren’t that many jobs that have that criterion, however. You could argue that we need to get better at reaching out to an electorate that keeps putting anti-science ignoramuses into high office, but that does not imply that everyone needs to become a PR expert. People who can inspire students and can generate new knowledge are still essential.