> Never scan QR codes: There is no evidence of widespread crime originating from QR-code scanning itself.
> The true risk is social engineering scams...
Exactly. My grandma is very susceptible to phishing and social engineering, I don't want her scanning random QR codes that would lead to almost identical service to the one she would think she is on and end up with identity theft or the likes.
> Regularly change passwords: Frequent password changes were once common advice, but there is no evidence it reduces crime, and it often leads to weaker passwords and reuse across accounts.
Forced password changes are one of those security theater exercises that drive me absolutely nuts. It's a huge inconvenience long-term, and drives people to apply tricks (write it on a post-it note, or just keep adding dots, or +1 every time).
Plus, if your password gets stolen, there's a good chance most of the damage has already been done by the time you change the password based on a schedule, so any security benefit is only for preventing long-term access by account hijackers.
Sure, if you use unique passwords, then changing passwords isn't as useful. Yet we shouldn't judge a security policy based on the existence or not of another policies.
What you are judging then is a whole set of policies, which is a bit too controlling, you will most often not have absolute control over the users policy set, all you can do is suggest policies which may or may not be adopted, you can't rely on their strict adoption.
A similar case is on the empiric efficacy of birth control. The effectiveness of abstinence based methods is lower than condoms in practice. Whereas theoretically abstinence based birth control would be better, who cares what the rates are in theory? The actual success rates are what matters.
> The true risk is social engineering scams...
Exactly. My grandma is very susceptible to phishing and social engineering, I don't want her scanning random QR codes that would lead to almost identical service to the one she would think she is on and end up with identity theft or the likes.
> Regularly change passwords: Frequent password changes were once common advice, but there is no evidence it reduces crime, and it often leads to weaker passwords and reuse across accounts.
Database leaks happen all the time.