I mostly agree with the points you bring up.

The main reason I am calling this an exploit is because you never level sync but gain full rewards with much less contribution and considerably less danger than if you level sync.

Remember, when you level sync, stats are capped to the level you sync to which in turn affects potency. A cure spell cast by a level 50 whm is much more powerful than a synced level 30 cure. Also if I avoid syncing below level 36 as a whm, I keep granite skin trait (18% vs 10%). In addition, because I'm never technically in combat, my mp and health regeneration never go down. I cast a spell, and immediately my mp goes back to full. I get hit by a monster in the fate because I gained aggro and my health goes right back to full.

Ultimately I just want this to be brought to the devs attention (if it isn't already) because I don't think I should be rewarded if I'm never in any actual danger. In order for DPS to contribute and gain rewards they have to level sync. It's not balanced that a healer can avoid it and still gain rewards. Now, I have not tested if it is possible to gain atma drops using this - but since I am able to gain full rewards otherwise, I don't see why not.