This list has already jumped the shark.
There are no metrics, including the eye test, that have Oates and Dionne as top 5 playmakers of all time.
Using era adjusted assists for both career and single season totals, Francis, Jagr, Thornton, Forsberg and Crosby all rank higher as playmakers.
McDavid could easily be top 5 by the time he retires as well but it may be too early to rank him there.
There is definitely a metric for Oates. I think looking at finishes relative to your peers is one of the best (but obviously not the only) metrics to use when determine if the greatest of something. And based on that metric, none of those players have the edge over Oates.
You can disagree on whether you think he’s top 5 based on other things, but you can’t at all say “there are no metrics”.
Oates: 3x leading in assists, 12x top-10 (finished second to Gretzky once too)
Thornton: 3x leading in assists, 12x top-10
Crosby: 1x leading in assists, 10x top-10
Francis: 2x leading in assists, 12x top-10
Forsberg: 1x leading in assists, 7x top-10
Jagr: 3x leading in assists, 10x top-10