To obtain the Element Spark, a Carrier had to kill a creature with the suitable element. This meant that in most cases, there were many options.
Only if the Carrier had a truly rare element would there be limitations in the choice.
If Ethan had to find a creature with chaos, he would be one of those Carriers, but he had another option: darkness. As became clear from his trip to Louis's shop with Menir, darkness was not nearly as common as fire, but still not as rare as chaos.
Ethan had enough options to give the fragments a variety of choices. They led him to the Desolate Meadow not because it was the only place to find a creature with the darkness element, no, even in Orsire City, there were more than enough.
It just happened to be the fastest and most efficient option for him. The quality of the Element Spark wasn't crucial, but it wasn't unimportant either. It affected the strength of the First Ring and the speed of the Circle's rotation after evolution.
