I blow as many leaves as I can to the front yard where the lawn is. We have Oak, Elm, Tallow, Hickory, Pine needles, Youpon, and a host of neighbor's leaves. Yes, it is tedious work with the gas blower. But when mowed over it and bagged up for spreading makes the best mulch for the winter. What little is left on the lawn helps it to overwinter as well.
I have been using mulched leaves in the back beds to build them up with bark mulch to top it off every spring. This year, I will use mulched leaves in the front beds. This also saves when using bark mulch later in the spring as a topper.
I know this doesn't answer the question of whether mulched leaves or whole leaves are harmful. But as someone pointed out, nature's leaves are not mulched up and the wild flowers seem to do fine with it. Plus my soil in my beds are super rich!
