This question asked for a very basic definition of pairs trading for explaining to laymen. I've seen quite a few other similar questions. I don't think this provides anything of interest to "traders and professionals" working in the industry. This is essentially an exercise in investor education and/or marketing. A google search would have found many laymen-friendly explanations.
I don't think these types of questions are categorically off-topic. There may be times where "traders and professionals" have to explain complex topics to laymen (investors, executives, etc.) and it's generally a difficult task.
However, most of these types of questions (that have been asked thus far) are too broad and it seems the questioner is the layman. A question should be closed as "not a real question" if the entirety of the question is, "explain XYZ to a layman".
The question should be allowed if it demonstrates knowledge of the subject and specifically identifies the portions of the subject that are difficult for laymen to grasp.