I installed the first Audimax and Volumax combo in South America in the earlier 60's. Compared with other stations in my market, Quito, Ecuador, it made the station sound both loud and clear. Previously available gear was very poor on AGC action and the Audimax did this very well without significant artifacts. The Volumax was a single band compressor and limiter, so it could make some songs with very "loud" single instruments cause the whole audio spectrum to be unduly limited.
But the Volumax was gentler on peak limiting than earlier products, and if used with the Audimax, it did not have to attack as much since it was provided with already leveled audio.
What few took advantage of was the third element of the CBS gear: the Dynamic Presence Equalizer. In effect, it looked at what it considered the "presence" band of each audio element and made sure that it was not buried by the bass or higher frequency components of audio. It tried to identify the presence band of each item (song, commercial, etc) dynamically and was pretty good at it. I had them on all my contemporary music stations, and it made them sound "crisp" and "clear" (listener comments).
None of the products back then were multi-band. And none delayed the audio so that the processing could "read ahead" and control the full waveform rather than attacking it when it got "too loud". That was more than a decade away.
The most significant reason to use that gear was that it made a station sound much better than competitors who did not have it. Today, the only reason to use the pair would be to try to emulate the sound of stations from that era, requiring dubs from the original records as well.