> this has been watered down a lot by the way-too-common practice of storing TOTP secrets in password managers

I'm open to discovering I'm wrong here, but I have never understood this line of thinking. Assuming you 2fa into your password manager when you first sign in on your device, it's still 2 factors all the way down.

As you sign into your password manager, the "something you have" is your 2fa device that you use to sign into your password manager (which is obviously not being filled in by your password manager). Subsequent password manager unlocks which don't prompt for your token are still 2fa because the "something you have" is your computer with which you signed into your password manager.

Why is this a problem?