1Password is not the only password manager out there. There are others, like LastPass and KeePass that work differently and are free.
Using a dedicated password manager is mostly for convenience; I don't need to save the same password at 3-4 different places like Keychain on macOS/iOS and Microsoft Edge on Windows. They usually have extensions that allow to integrate with different web browsers on traditional computers, or with the operating system on mobile devices.
If you use a long password, which in an ideal world everyone would, the password would always be saved in your password manager. For example, 1Password does provide you with a website where you can access your saved passwords, if you sync with their service and you provide the login page with your email, your password, unique encryption key and second factor authentication method.
I understand what you mean regarding the password manager
For the long password thingy
let say, in some occasion, you don’t have access for your usual devices, and you need to logon to your email urgently, you need to either borrow someone’s phone or internet cafe to do that. With the impossible to remember password generated from password generator, you need to login to your password manager website so you can access to those random characters. And another thing is, the main 1 password for the password manager is the key to all your password right ? Do you use long character as well ? Since this is the gateway which need the most security ever. How to remember that long random characters ?
I’m just curious, if I really rely on the password generator to create such characters, I felt that I have no control and no ability to remember, on something crucial