iCloud Keychain is pretty good, but it tragically fails in the followings cases:
* Any browser other than Safari.
* Apps that MacOS/iOS don't parse for password fields for some reasons so you can't generate a password right there — and it's a huge pain to add them manually, practically impossible on iOS.
* Cloud access (if you need your account and don't have any of your devices). Your Keychain is in the iCloud, but you can't access it from icloud.com
So Apple could easily make it much better but they haven't.
