I think it's been greatly over-thought.

Here's how I interpret the distinction. The Echo is just a naturally occurring phenomenon. That's all. Some people have it, some people don't. Now, the Echo allows one to do things beyond normal mortals, including being able to understand the lifeforce (Hydaelyn and Zodiark represent the duality). What this means is that Echo allows for Warriors to be chosen to fight on behalf of each duality. Not all Echo users are chosen though because not all are strong enough to fight. The ones chosen to act as Warriors are given the ability to see and collect Crystals. The more Crystals one collects, the stronger the bond between Warrior and Lifeforce. The ability to collect Crystals is strictly dependent on the skill of the individual. Nothing more. The most naturally skilled of the Crystal Bearers is the Chosen One, or Champion, as he/she will be able to collect the most Crystals and thus, have the strongest bond.