i agree with you, though i wonder if often we think that we used to be some type and simply didn't recognize that it was reasonable function use for our current type.
i experienced the same perception that i was Fi dom when i was younger, but, after all, Fi is Judging, internal, and, for me, the "supportive parent", which means it will be fairly visible. on the other hand, sometimes it can be easy to overlook your dom if it's a Perceiving function because it's more like an "ocean" that you swim in. i never realized the ridiculous extent to which i was N (though it always was my strongest letter in testing) until i learned what Ne was and what you see with it. Fi seems more prominent through my childhood, however, because i wrestled with it more. Ne was just... well, like swimming. it was simple and natural. i thought everyone thought like that.
so while i can understand someone who had amnesia or a mental breakdown of sorts having the possibility of restructuring (though i still doubt they'd move far from their type), i would venture to guess that for most people who think they've changed types, especially since childhood, it could be useful to look more closely at function order and see if perhaps one of the functions was most visible for whatever reason, and later moved to the background.
as far as the connection between neurology and type... well, personally i've gotta leave that to the neurologists
i would love to see it studied, though.