Old vs New problem
"Persuading users to use stronger passwords is an age-old problem that dates back to the dawn of the PC era."
It's not an old problem, it's a new problem.
In the old days, you had about 3 passwords; you had to convince the user to make them strong. Once they were strong, you could use them for a long time because they were secure. Because you didn't change them, you could remember them.
Now, we all have a dozen or so passwords. If we make them strong, they're hard to remember. The harder they are to remember, the more likely we are to reuse them. Because some people use weak passwords, corporate policies add a layer of security by forcing us to change them every few months.
I can remember every password I had on the computers at uni, because I used them frequently for a long time. My password for the office PC expires so quickly that I've barely learnt it by the time I'm asked to change it. The cognitive load is high, and every time I sit back down and unlock my PC, I have to filter out "noise" from half-a-dozen old and "other system" passwords before I get to log in.
So my passwords are getting weaker all the time as it's the only way to remember them.
It is a new problem -- it just looks similar to an old one.