If you look at the top ten in primary assists vs the top ten in secondary assists there is very little overlap. For instance over the last 8 seasons only 17 times a player has been in the top 10 in both, compared to 155 times that a player appeared in the top 1o in one, but not the other. Secondary assists are more a measure of the quality of the teammates on the ice with you, and your PP time, as well as if the powerplay is built around you.
That most of this thread is simply people reacting based on their love of McDavid and their hatred of the Leafs/Matthews, is especially stupid considering that McDavid is 3rd in primary assists this season, and tied for 28th in secondary assists, along with being first in primary assists last year and 4th in secondary.