Let me unpack that one a bit. Keys work because users don't have to memorize the shape of every one of their dozens of keys, and recall every detail of them blindfolded every time they need to unlock stuff. They just need to be able to recognize the right key from the set on their keyring. Nothing sensitive is given away if they can't, and just try them all one by one. The key does all the important memorizing about how to open the lock it goes with.
AFAIK passwords were a security measure originally designed for multi-user mainframes. Computers whose users were generally known to each other, or at least affiliated with the same institution, and before the emergence of ubiquitous networking, usually airgapped. The consequences of security failures were not world-shattering, and users generally didn't have dozens of passwords to remember.
Everything about how computers are set up and used has changed since the invention of passwords, except that we still secure almost every kind of user identification with passwords. I think we need to take a step back, and completely rethink what we're trying to achieve with passwords and password managers, from first principles.
From the basics - computer security has three factors - "Something you know", "Something you have", "Something you are". There is nothing more. Passwords are the "know", while certificates or keys are "have", biometrics is "are". 2FA means using two factors together. If you think about it, password manager is actually already 2FA, because you need to "know" the master password, and "have" the password database file. So it's actually a step up.
@chebra thanks, this a very clear, concise summary. Can you recommend a good link for a first principles discussion that lays out things like those 3 basic factors?
Hmm, I actually learned that at uni. Maybe sources like Khan Academy could have more of that ground work. But mind you, good passwords are about the best thing we have. Each factor has its downsides (such as you can never change your biometrics if they get compromised) and passwords became so popular because the downsides are smallest. Every bit of convenience sacrifices a bit of security.
@strypey Yeah! For an example bitwarden uses the same practice, it has master password so to hack all ur passwords they just need to crack master key of RSA they store on their servers :) People should use KeePass or stuff like that to be really secured! KeeWeb is also gut!