Defending the singular ‘they,’ the Baltimore Sun’s John McIntyre makes an important point:
I do wish people would stop talking about what is “logical” in English. Languages abound in elements, such as idioms, that make no logical sense. I wish they would be clearer about distinguishing rules from personal aesthetic preferences. There are plenty of rules, like the order of adjectives or subject-verb agreement—though the latter is a good deal more complex than addressed in the fifth grade. I wish that more people were willing to throw the rubbish overboard—bogus rules, superstitions, class shibboleths.
You Dont Say: Are you smarter than a fifth-grader?
See also: Dogma vs. Evidence: Singular They