If we go deep behind the "why", it can be summarized as:
- Pure CSS. if you don't need js for animation its always faster, GSAP is JS, avoid JS for all animations that don't need it, especially reveal animations
- Webflow interactions can be hard to use because there is no way to select many elements and apply an animation on them.
- Motion One is based on web animations api, which is a JS api. It's still going to be worse than pure CSS. Motion One as a library is a lighter weight modern alterernative to gsap, I am not sure which features gsap has that are impossible with motion one