The problem here is that the built-in password managers often have no password protection and this means that your sensitive data is not encrypted and is in plain text. (Safari does not have this issue.)
Also Chrome does not have this issue if you protect your phone with pin, password or fingerprint. If you go to chrome where you will see it, you can not know the password without using your device passphrase to access it. But one thing I disliked about the password manager is that it is online. The second thing I disliked about it Google password manager is that if you want to login on a website, the password and the username will autofill itself and if you check on show password icon on the website, you will see the password in plain text which makes what you posted to be partially true. I guess that is it would also be on Safari. Or isn't it like that on Safari?