Leaves are valuable. They make good compost which is useful for
gardening, vegetables, flower gardens or even on lawns if chopped up.
It's a shame that so many people waste so much time and energy raking
up leaves, bagging them, then sending to be hauled off, when they
could be piled up for compost. Or, here in the South we have a
landscape form called 'natural area'. You can also blow them into
natural areas with your lawnmower, leaf blower or just rake them.
If they are allowed to just pile up on grass, you'll likely damage the
grass. Of course if you want more natural area and less lawn, that's
not a bad idea either.