You are going to love this theory. I guarantee it.
I was reading Andrew's article the other day, and that got me thinking about what makes magic work on a fundamental level in the cosmere. This will be somewhat of a rebuttal to you, Andrew, because this direction is far more fruitful. But it's much more than a rebuttal. In my opinion, this is quite a paradigm shift.
In any given Shardworld, magic is directly tied to a Shard. Everyone has pieces of Shards inside them. In Mistborn, everyone has