You can't use the AR and MK score shown on your ASVAB Score Sheet. The Score Sheet shows "number correct" for your AR and MK Scores, because "number correct" is what is used for job qualifications. However, the military does not use this same score when computing the AFQT. They use the "weighted scores" of the ASVAB sub-tests for AR and MK. Harder questions in these areas get more points than easier questions. The "weighted scores" for AR and WK are not listed on the ASVAB score sheet given to you after the test.
The various armed forces adopted all of those aspects in 1976. At that point in time, the test was in its written form rather than today’s more common form (computerized test format). The written form covers all of the previously mentioned areas as well, which is why both forms are still available. All-in-all that answers the question concerning the intention of the test.