Raking leaves into piles and then onto tarps or large vacuum machines seems to just be a normal part of fall cleanup before winter hits. Recently, authorities have been encouraging us to mow the leaves and let them mulch into the lawn. There are several benefits to be had from this practice, not the least of which is that it is a whole lot easier. You should know why mulching is better.
Adding ground up leaves that are mostly carbon by the time they are mowed, provides a nice organic material that can soak up rainwater and hold it for the roots of plants to absorb.
Lawns that are raked or vacuumed clean of all the grass trimmings and fallen leaves will have no source of nutrients or new organic matter without artificial feedings. If the mulched leaves are left for the worms to work through, the fiber from the leaves and the worms will aerate the soil giving it better texture.
Yard waste can fill up our landfills unnecessarily. Instead of treating it as a waste, it should be treated more as a soil amendment. You can save the space for things that are really trash.
In 1990, MSU's Hancock Turfgrass Research Center conducted research on the effects of mulched leaves being left on the lawn and the end result was consistently a better lawn with no changes in the pH. Some debris was visible in very thick layers of leaves, but as soon as spring growth started, the debris was gone.