Why are they calling it 'attention' if it's just a weighted average?
Human attention is something very different.
Like an accountant not realizing that addition and multiplication are special cases of a monoid operation.
Aside from that, kernel smoothing has roughly 70 years of literature devoted to every practical aspect you could imagine: approximation, accuracy, pedagogy, behavior under sparsity, relationship to other well-known theories like Bayeisan learning, and so on. Variants like Performer and elliptical attention, all directly arose from the knowledge that attention is intro-grad-stats kernel smoothing. A large portion of our understanding of ICL is directly or indirectly resultant from the fact of this correspondence.