"Learner" is a piece of jargon of relatively recent coinage and limited meaning. I am a teacher in the field of adult basic education, and I therefore read what purports to be literature on education designed for professionals. And in a number of these articles, the term "learner/learners" is used to describe students.
If you read the last word of that paragraph, you see the word "students". "Students" is the word used in spoken English to describe people that learn. "Learners", while an understandable grammatical construction, sounds stilted when heard or read. Since we already have a nice, natural word to describe something, why replace it with an artificial and redundant term?
The only good reason I can think of is that while "students" has the connotations of a traditional age student who is enrolled in a formal institution of higher education, it might somehow exclude people who are studying at, say, an employment retraining program or in a correctional facility. The term "Learners" could be seen to be more inclusive.
Except that is not the real reason the term is used. The term is used because it is jargon, and by replacing a natural term with an unnatural one, certain segments of the educational establishment hope to make the amorphous, non-technical field of education appear more technical. "Learners" is what you say when you are jealous of people who get to use terms like "parachlorophenylethylamine". Someone who is saying "Learners" is also probably trying to sell you something, and I immediate go into distrust mode when I hear the term.