I think the main problem is that there's usually an unfortunate trade off between usability and security, and most of the issues mentioned as dumb ideas here come from trying to make the system less frustrating for your average user at the expense of security.

For example, default allow is terrible for security, and the cause of many issues in Windows... but many users don't like the idea of having to explicitly permit every new program they install. Heck, when Microsoft added that confirmation, many considered it terrible design that made the software way more annoying to use.

'Default Permit', 'Enumerating Badness' and 'Penetrate and Patch ' are all unfortunately defaults because of this. Because people would rather make it easier/more convenient to use their computer/write software than do what would be best for security.

Personally I'd say that passwords in general are probably one of the dumbest ideas in security though. Like, the very definition of a good password likely means something that's hard to remember, hard to enter on devices without a proper keyboard, and generally inconvenient for the user in almost every way. Is it any wonder that most people pick extremely weak passwords, reuse them for most sites and apps, etc?

But there's no real alternative sadly. Sending links to email means that anyone with access to that compromises everything, though password resets usually mean the same thing anyway. Physical devices for authentication mean the user can't log in from places outside of home that they might want to login from, or they have to carry another trinket around everywhere. And virtually everything requires good opsec, which 99.9% of the population don't really give a toss about...