The point of a password manager is to have different passwords for all the services you use.
IT DOEN’T MATTER HOW STRONG YOUR PASSWORD IS IF AN ATTACKER CAN SEE IT IN PLAIN-TEXT.
Each service you use - Google, Twitter, Facebook, Netflix, Amazon, Office-360, this forum, your bank, etc., takes your user name and password to authenticate you. This means that at some point, your password is exposed in plain text to the server. Some services have better “best practices” for password handling than others. In other words, it is a good bet that one of the services you use has weak protections for your password.
If one of these servers is compromised, the attacker now has your password. Not so bad if someone gets into your Twitter account and posts stuff. If you are like me, you have no followers anyway. Someone hacking my Twitter account might actually make me more popular…
But if someone hacks your Twitter password and can then use it to access your bank account and your Amazon Prime, you have problems.
The best practice to compartmentalize services on the web is to use a different password - strong, non-derivative - for every service you access. If you can remember that kind of password or passphrase for every site you visit, please share your memorization method, because that is very cool.