There are a number of things I learned as a child which don't make much sense to me now. Among them, the scientific method, color theory and the six simple machines:
http://atlantis.coe.uh.edu/archive/science/science_lessons/scienceles1/finalhome.htm The six simple machines are: lever, inclined plane, wheel and axle, screw, wedge and pulley.
In both cases, I wonder what the rational was in creating this particular generalization. Perhaps it is helpful in teaching concepts. However, in hindsight, the generalizations don't really make much sense. That said, is there perhaps a more up-to-date generalization for "six" simple machines that will one day, too, look a bit unintelligible.
For all intensive purposes, it could be: for, if, else, while ... hm that's only four.
Or, it could be: union, intersect, concatenation ... hm that's only three
Or, it could be: insert, delete, sort ... hm that's only three
and none of these feel truly unified.
I mean, seriously, generalizing tools only makes sense if one has an idea for a machine model in the first place.