The assertion of the existence of 16 types appears now to be the assertion of 16 ideal types, types where health and balance exist. To keep the faith, one would tend to assert that whatever real types exist, they are corruptions, or less than ideal instantiations of the ideal, people who've emphasized for whatever reason one aspect of their type at the expense of another.
Last time I did a function strength test, I came out Te>Ni>Fi>Se, but I don't believe that result. It would seem to imply, though the Te result was only slightly higher than the Ni result, that I should be an extrovert, and I know from real life that I surely ain't. So I put it down to doing the test questions wrong.
So I guess that makes me one of the faithful. I believe.
So, which comes first, the functions people manage to test as having or the ideal orders MBTI thinks they should have? People are people are people, yes, but and perhaps this is just the Te talking, people are works in progress... they're on their way to the ideal.