The only thing I clean up are my pear and apple leaves because they can carry fungal spores on the leaves and if I remulch them in it becomes a neverending cycle of leaf spot and crappier fruit.
I don’t want a lot of non-native weeds, but I do like the dutch white clover. So I let that grow like wildfire and over the years it has spread throughout the lawn and helped the grass (and I assume nitrogen) as well.
But yeah, I think mulching in healthy leaves has more positives than negatives. Nature generally knows what it’s doing.