From the engineers' prospective, you can add processing such as echo, reverberation, phasing, flanging, to any clean recorded sound, but you can't remove it. By recording electric instruments clean they're free to add processing later.
Imagine if you could only record at one volume and not mix the tracks later.
I've recorded tracks with echo and lived to regret it, when, at the mixdown stage it becomes obvious that there's too much echo, and there's no alternative but to record the track again. I wasted hours like that until I decided to lay down the tracks clean.
But I can see Jerry Byrd's perspective, too. He had a particular sound that he's developed, and wanted to stick with it. But again, as Basil said, Jerry was a big enough star to be able to dictate terms, most other people need to do what they're told if they expect to keep working.