::::::::I agree with Iblardi, also the word "infrequently" adresses your valid point it is not common; while inclusion is validated as the provided reference provides irrefutable evidence that the use does exist. So I think this should be a solution acceptable to both points of view, and hence neutral. (Also note that I started out believing in your claim it should not be mentioned (null hypothesis), but after a quick google search provided evidence of the contrary (my search for the "black swann" yielded one in the form of Britannica) I had no alternative then to change my opinion.)