Dear Roomba, please make this a real product. xoxo
With cameras and basic spectrum analysis to identify leaves, sonar/lidar/3D cameras to analyze the topology and a little participle physics, it could probably be automated. Tell it where you want the piles and where the borders are and let it fly.
Has enough money for a really nice drone.. doesn't have the money to buy a 15 dollar push broom(the proper tool for this job).
Probably more a matter of convenience. His current broom broke and he had the drone handy. A replacement broom would mean a trip to a store, plus the money for it, plus the time to still do the sweeping. Had he started with the drone, yea that's just questionable.
To be fair, push brooms are rather large and clunky to store.