For a random website, no, for bank and primary email (used for account recovery), they probably should.

It honestly takes a minute to add a key and it's just that, a physical key.

IMHO what's risky in terms of UX and habits is precisely that most workflows do not highlight this. So people rightfully are scared of losing that 1 precious key, so they don't activate 2FA because of that. Meanwhile if the UX when they activate 2FA would clarify that they only have 1 key stored, adding a 2nd one or saving codes (most do propose that option for 2FA authenticators but not hardware passkey AFAIK) is what will make them both safe against attacked but also against their own accident (shit happens) then maybe behaviors would change.

Anyway, yes, you're right, most people don't do that or aren't even aware of it but arguably as more and more important and intimate part of our lives are online, it becomes crucial for one owns sanity to better understand how this all works.

> For a random website, no, for bank and primary email (used for account recovery), they probably should.

Even for this, for grandma, this is probably still asking for a lot.

Grandma's bank will have a recovery option even if she's tossed her phone, computer and hardware token in the ocean, and then had a stroke which made her forget any passphrases or whatever: You can call the bank and physically authenticate yourself with a passport, driver's licence or some other ID. It's a bitch to do, you may have to go to an actual bank branch, but grandma will get access to her money again. Meanwhile, her access to physical mail doesn't stop just because she's forgotten some passphrase or lost her phone.

Even techy people get caught out by Google forcing 2FA, while casuals don't even consider the possibility of losing access to their email. While both the rhetorical you and grandma both should probably have a bulletproof recovery option for their email, since it will be the foundation of their digital identity, getting them to acknowledge the problem is going to be hard, and the solution, paying for a Yubikey or some other house of cards solution, is a tough sell.