Why? It depends on your scenario. If it is “attacker gets hold of my wallet” then yes, you’re screwed.

But 2FA still helps if a single password was leaked/bruteforced/phished, and afaict most password managers in autofill mode recognize the browser url, so it’s quite phising safe (2nd factor won’t be autofilled on wrong website)

Security is not binary, and 2fa via password manager is still much better than no 2fa; it’s not pointless.