Student was such a nice word, too. One could be a student at any age, and it had such a hopeful, optimistic quality.
Compare the following conversations:
"What are you doing with yourself these days ?".
Oh, I'm a student at the University....; or, I'm studying ......".
to
"What are you doing these days ?
"Oh, I'm a learner at the ....?"
Learner falls flat, sounding institutionalized and dreary, as if there was nothing wonderful about the experience at all.
True. My guess is that the term derives from behavioral psychology, as in stimulus/response; stimulator/learner.
Behavioral psychology dominates ed schools. It amazes and saddens me that the modern model for teaching derives from Skinner's rat experiments.