Prior to the 1980s, process control was in the dark ages.
Our main technology was the single-loop controller,
despite that it operated obliviously to the many interactions
and non-first order responses that characterize most processes.
Due to cumbersome capabilities, usually involving hardware and
wires, if not tubing and pneumatics, any enhancement, such as
feedforward, override or adaptive gain, was undertaken only for
the most demanding or profitable loops.