Yes, exactly. I could not have said most of this better myself. (I love LII's...)
On duality/ILE's: Having grown up/gone to college in environments where I had to constantly hide my true self as a form of self-preservation, and finding my first real ILE friend post-college and becoming astonishingly close to that person just as I was pushing to be a stronger person and be myself...and having that person pass away...it's not like I consciously need that person or even NeTi on a daily basis, but when I encounter it it's like I ache for entire parts of me that I had forgotten were missing and are only then becoming reactivated.
For instance, just last night I met this ILE man I had randomly contacted via couchsurfing not having a clue of his type (I just moved into a small rural/artsy town by the mountains for the next few months and don't know anyone) and suddenly it was like I needed some kind of sustenance that was just missing and which I was viscerally craving for, and I needed so much of it that only an extrovert could have provided that. (Missing a dead person is a completely different thing.)
All this is to say that I do think that duality is important in some capacity or another--not necessarily romantic. It helps readjust your mental landscape and remember who you are--or can be--as a person. Growing up with your dual, or around others in your quadra, might help stabilize certain "natural" aspects of you so that you don't necessarily need the presence of a romantic dual in your life, but even then they're useful for recharging/life-advice/etc etc. I do think that activity is almost just as good for this, since you're basically receiving the same functions, just in a different order.