you summed this up rather nicely, I was coming to post something similar.

His premise "things are things, not strings" things as he calls them, become more than strings in their usage, not transport, so things aren't "things" until you attempt to use them, until them, they are just data being transported from one place to the other, and the sender can not always know what system will accept them, so strings are a safe bet, if both sides are aware, and account for it.