Nope, they are not.

> What's the benefit of bundling

Even not running around and configuring a separate IMAP, CalDAV, CardDAV, SMTP account settings would be a solid improvement.

Runing over one endpoint instead of 3 would be a fine addition too.

Not using a ridiculous STARTTLS would be a good thing too.

> if someone only needs mail can only use IMAP/SMTP?

That's not a protocol question, it's a MUA interface and configuration question.