Having a working Chatper-creation-system in place would absolutely not preclude putting ample fluff into the book for the hard of surfing. Indeed, done right, it could open up the Chapter variety fluff for everyone. I could personally write a roughly four page essay that shows the massive variety of SM Chapters for example that would give rookies ample to work with as a kick-start.
I also think that a more detailed write up on a couple of Chapters would also be desireable.
Hell that would be stacks more than we got in the 1e 40K rulebook ... and though we were all new to the setting when that came out, I don't recall people struggling to grasp what SMs were then.