You're the first person to ever explain--where I've been able to find it, anyway--and I've read the main books and taken the tests that have explanations and the rest... why I test close to the line for F/T.Heatly IxxJs and ExxPs show great balance between feeling and thinking because it's in the middle of their stack. Likewise, healthy ExxJs and IxxPs show great balance between Intuition and sensing because it's in the middle of their stacks.
It's hard to find for example an ExTJ who is just as empathetic lovey gooey as they are hardcore rational. The latter just has too much weight over the former. It CAN happen, perhaps if they are really experienced and wise.
For instance Dr. Phil (an ESTJ) ''I really want to help you, it's ultimately my mission (Fi) but it's just way more fun to list the reasons why you're a sh*tty irrational mess and get my audience clapping at me (Te)....''