Ahh, yes, I see your point.
Staying more or less within mathematics, I'd say "intersectionality" derives more from network theory than from set theory in that an intersection (technically "vortex") is a place where lines ("edges") converge.
More practically, I think it's intended to evoke a navigational metaphor -- an "intersection" of multiple roads.
In a sense, tho, it *is* intentionally restrictive in that something is only intersectional if it has more than one path.
cc: @nex3