Before it
One formulation of attention existed, using a small feed-forward scoring network.
The problem
That scoring step was expensive and its design choices untested.
What it introduced
Simpler multiplicative scoring, plus global and local attention variants, compared systematically.
Why it matters
The dot-product scoring the Transformer uses comes from this line of simplification.
What modern models inherit
Dot-product similarity as the scoring function inside attention.
What came next
Scaled dot-product attention in the Transformer.