It is, or at least can be. Flexible systems are like that.
but at the same time, we're likely talking about multiple systems,
and/or systems with different operating modes. The typical user doesn't
need real-time token generation for web pages, what they want can be
stuffed into a mail client and doesn't require any server side at all.
Handle it all at the MUA level if you want. and it wouldn't be the
first time someone built a system with an "expert mode" that hid
secondary features until a user decided to tackle them....