I suppose this is a problem if someone breaks into your home and gets into wherever you keep your notebook and steals it but frankly that's hardly the only problem you have in that scenario.
I think this is bad advice - it encourages password re-use, and gives insider threats a perfectly simple vector for credential theft (because you need passwords at work as well as at home).
Also that advice is from 2005, I wonder if he'd agree with what I said above or disagree.
Not true, as it turns out. I created passwords for my users and put them on a laminated card as a courtesy, with instructions to keep it in their wallet, purse, etc. They were turning up stuck to keyboards, shelves next to desks, etc. Some people are really crap at securing small pieces of paper.
Even if you assume many of those sites I don't use anymore, we're still talking a shitload of passwords I'm supposed to have written down somewhere.