I didn’t invested too much time into hardware keys but requiring additional software on other PCs, still is a no-go for me. With my current setup, I only need my smartphone and I always carry it around.
For business use, this is a whole different topic. With a proper setup, all machines would require the software and you shouldn’t access these accounts outside from company devices. Its also an expense which the company must carry and its easier for them to handle backups. Also in that Setup, you can have SSO/LDAP, where you can physically proof that you are you and requesting resetting the MFA. With an online service, they usually require a weak proof, like just the access to an email account.
I just needed to think of the scene from the Simpsons, where Mr. Burns and Smithers go all through the security checks and in the end, there is a flimsy open backdoor, where a stray dog entered the room. All security in the front doesn’t matter, if the backdoor is not secure at all and until the backdoor is that unsecure, I’m not willing to add money and time, to make the front door more secure.


I quote myself from a different comment:
The phone argument lacks a bit. Accessing the TOTP App and the password manager do require a separate authentification, to get encrypted. Sure if they snatch my phone away, when its fully unlocked, including my password manager, they have access for a limited time. They need to be fast enough, until I can remotly lock it or until it automatically locks itself. Android phones can now detect when they are stolen. Either by the movement or when it goes offline. The latter I tested and it’s not instant, but you still don’t have long.
I don’t think about potential backdoors. If there is no known backdoor, then I deem it save. Sure they also could me to unlock the phone. This would be xkcd 538. And this applies to any security.
Adding more security and inconvenience doesn’t make sense to me, so long the backend is shit. So far a few big companies did screw up hard in their backend and dozens of smaller sites do some bad stuff, that it doesn’t really matter how strong your login is. Here I reference back to my quote.
In a closed system, like a company, this added security makes sense, as they usually control the backend as well. If my CEO would send me a text request to reset his logins, I would call him or walk to his office, and ask him directly. Sure with AI, they could impersonate his voice but I don’t think they can impersonate his way to speak.