Leave the leaves does not mean ignoring them and leaving them where they fell. You can move them to places in your yard where they are out of the way, will not kill your turf, and will still help wildlife. A thin layer of leaves can actually help turf—but too much will kill the grass. Consider raking leaves into areas around trees, or use them as winter mulch for perennials or to cover garden beds.
Another reason to leave the leaves is for the benefits they provide to your landscape. They help build healthy soil for your plants and have the same weed suppression and moisture retention as shredded wood mulch - and they're free!
One of the most valuable things you can do to support pollinators and other invertebrates is to provide them with the winter cover they need. Leaves are not litter - they're food and shelter for butterflies, bees, beetles, moths, and more.