I flew an ex-Air Canada DC-8-61 a couple of flights a long time ago. What a mess they made of that cockpit. F/E panels relocated everywhere, and there he sat with less than half a panel asking us to do this and do that he could not reach himself. We hated that airplane.
We were told AC actually never was allowed to fly them without a F/E (or S/O) so the whole thing was in vain. Would be interesting for someone from
that era at Air Canada to confirm.
Anyway, for better or worse, much of the traditional systems knowledge was removed from the training and manuals.
And, I would observe that this trend has continued in the decades since.
Agreed, the Boeing manuals (dunno about others) have continually been "dumbed down".