In the electric era, most of the time only a mic replaced the horn. By the 40's, sometimes multiple mics were used and the producer chose the best sounding take from that (Rhino put out CDs of stereo film recordings from that era).
In the late 78 and mono LP age, the engineer had more tools including equalizers to adjust the sound.
You're certainly correct that in the past decades (maybe six decades), recording engineers have at their disposal an infinite variety of sound altering tools. The most knowledgeable who understand their equipment also make the best recordings. However, I'm amazed that the early stereo (mid to late 50's) recordings had the fewest alterations to the sound after they were captured by simple miking using 2 or 3 mikes. Those engineers were brilliant and had an acute grasp on sound and miking.

