The short version
Motion converts because it compresses comprehension. A visitor who understands the product in four seconds is dramatically more likely to continue.
What is really going on
Above-the-fold motion answers 'what is this?' before the visitor has finished reading the headline.
Demonstrating a workflow reduces perceived risk far more efficiently than a feature list.
Dwell time rises, and with it the probability of scrolling to the proof section.
How to handle it
Use a short, silent, looping hero animation — autoplay with sound is a bounce generator.
Show the product doing the one thing that matters, not a montage of everything it can do.
Keep the file small and lazy-loaded; a slow hero cancels the conversion gain entirely.
The takeaway
Motion is not decoration on a landing page. It is the fastest available explanation.