Theft: A $2000 laptop is an easy target for anyone with sticky fingers, and so is a $1000 smartphone. A Yubikey has essentially zero resale value, so you will not lose them due to random theft.
Durability: If you drop your smartphone, there's a pretty good chance you'll shatter the screen and buy a new one. You can play tennis with a Yubikey and it'll be fine. You can run it through the washing machine and it'll be fine.
Longevity: Laptops and smartphones generally only have a 3-5 year lifespan due to battery degradation, and many people will want to swap it for one with more storage or whatever anyways. A Yubikey will essentially last forever, and if you stay clear of the insanity that is Passkeys its Webauthn element can support an infinite number of websites.
Portability: I have a smartphone, a work laptop, a home laptop, and a home desktop. My Yubikey has USB and NFC, so it can trivially be used with all of them. Individually enrolling each device would be a nightmare, and having the credentials sync is a bad idea from a security perspective.
Security: If your device gets compromised, it's pretty much game over: the attacker can now log in to all your accounts, any time they want. With a Yubikey I have to physically insert it and tap the button for each login - which is relatively rare because active sessions don't tend to expire. This means I would have to actively participate in a mass compromise of my accounts, making it way more likely to be noticed.
Durability: If you drop your smartphone, there's a pretty good chance you'll shatter the screen and buy a new one. You can play tennis with a Yubikey and it'll be fine. You can run it through the washing machine and it'll be fine.
Longevity: Laptops and smartphones generally only have a 3-5 year lifespan due to battery degradation, and many people will want to swap it for one with more storage or whatever anyways. A Yubikey will essentially last forever, and if you stay clear of the insanity that is Passkeys its Webauthn element can support an infinite number of websites.
Portability: I have a smartphone, a work laptop, a home laptop, and a home desktop. My Yubikey has USB and NFC, so it can trivially be used with all of them. Individually enrolling each device would be a nightmare, and having the credentials sync is a bad idea from a security perspective.
Security: If your device gets compromised, it's pretty much game over: the attacker can now log in to all your accounts, any time they want. With a Yubikey I have to physically insert it and tap the button for each login - which is relatively rare because active sessions don't tend to expire. This means I would have to actively participate in a mass compromise of my accounts, making it way more likely to be noticed.