Browser-stored passwords: Why it is a bad idea to do it
It's not as safe and secure as a third-party password manager, even if Chrome and Firefox have security measures built-in to it

Storing your password on your browser provides ease of use. However, using your browser's built-in password manager puts your credentials at risk. There are security trade-offs to using your browser's password manager instead of a dedicated password manager. Whether you're accessing saved passwords on your handy tablet or through any web-browser-supported device, there are things you should know before using your browser's built-in password manager.