Why would anyone do that, when those digits can so easily be calculated or referenced from data files? Why do anything that is not strictly necessary? Why try to bench press more weight than last time? Why try to improve your chess game? Why learn a new programming language?
Because different people like different things. I am not required to like the things you like.
And I like proving to myself that I still can remember things without a helper daemon to keep track of them for me. I like that little bit of paranoid fantasy I have that makes me think that the men in black suits would have to take the pipe wrench to my kneecaps to get at my passwords, so I don't think about how the security at all these sites requiring password is so piss-poor that it would be easier to bypass all passwords in lieu of cracking just one of mine. In the end, the problem mentioned by the article is that very few people implementing computer security measures have any idea how to truly secure their data, so they do stupid shit like block clipboard pasting into password entry fields, or allow accounts to be hijacked by a spoofed SMS 2nd factor, or try to roll their own crypto without the requisite number of CS and math PhDs.
