A top level settings item called “Passwords and Accounts” is obscure?
Anyhow, this is becoming circular. I guess if you've used an iOS device forever you get used to its quirks, but it makes no damn sense if you use other OSes. Gmail, you can manage accounts within the app. Apple's app, you can't. Makes no sense.
HUH?? This is exactly why Accounts are a global setting.
What you are describing it literally EXACTLY HOW IT WORKS on iOS. Set it up once and it will work in Mail and Calendar