Unlike books and newspapers, old websites can be updated in design so that content looks up to date again without it being! Sure, you can release a new edition of a book or reprint the newspaper. Still, I would say it is not comparable to the simplicity of doing that to a website, most importantly the distribution part. For anyone visiting the website it will have a fresh look; the book would have to be rebought, and who does that when you still have the old edition?
For certain applications, I am absolutely sure this is a wonderful thing that has to be embraced. For others, I can see some problems; outdated data, scientific results or best practices should be clearly distinguishable as such. Not sure how to cope with that; never forget to look at the date of a blog post?
It can certainly be used for evil, will be, is used for evil; additionally, asserting the date – if there is any – as an outstander is probably impossible.