Maybe I'll start with what it was modelled after, which was major league baseball. I think it's working extremely well there. When baseball players were up for free agency, there used to be a long and drawn-out process, and it was very difficult to get the players and the owners to agree.
What especially works well here is that, because we're following that baseball style, each country is required to come out with a final offer that's reasonable and likely to be accepted by the arbitrator.
The arbitrator can't saw it off in the middle; they pick one side or the other. Even without getting into the arbitration process, the two countries are forced to make compromises and settle cases before even reaching arbitration.
Without that process in place, countries could just continue to disagree, not compromise in any way, be completely deadlocked, and then the taxpayer would have to pay tax in both countries. It's an effective way of forcing Canada and the other country to compromise and agree on solutions.