It doesn’t perfectly map, but it gets a visual point across. I cannot be convinced that it’s better for the average person to maintain a couple permutations of a primary password for a hundred different sites than it is for them to store it in a vetted and audited password manager. Even with the vulnerabilities mentioned in the paper you are far better off with a password manager and thus 100 fully unique passwords then without.
Yeah, but if you use the shack once per year, then why put the shack key amongst the ones you frequently use?