The flaw stems from the fact that an attacker can thru social engineeung acquire that root crendential (password or biometric or token). Once they have it, they can clean out all your banking, stock and home equity line accounts in one sweep. You as a user may not know that credential is compromised - maybe it was a key logger, maybe it was social engineering the cell phone provider to port your number and then qualify their phone with an sms token. You don’t know when that happened - you just see empty accounts.

With personal password managers, no third party is issuing tokens for access - just you. So it’s unlikley to be chosen for an attack - because it’s too hard for the attacker to acquire the credentials for access without detection.