Rule 1 is that password rules are bullshit, but all of the other rules lead to needing Rule 1: how are you going to explain to a user that their password cannot be their username, or that their password needs more entropy or complexity?
Of course, that comes with its own set of issues: Lose access to the password manager = lose access to all your accounts. An attacker gets access to your password manager = they get access to all your accounts.
On the other hand, for users who use a single 6 character word as their password all over the web, that's essentially the same thing. You can far more easily educate someone in picking a very strong passphrase they will never forget, than get them to use different passwords on each website.
I have successfully converted several non-techies in my family to KeepassX [https://www.keepassx.org/], which I also strongly recommend to anyone here. I had to hold hands at first but after explaining how it works and making sure they understand how important it is, over two years, there's never been any issues.