Hand Powered Mulcher

Why has no one invented a hand powered mulcher.  Seems like it would have gears like crazy so you could really crunch up a good sized branch pretty quick.  It'd fit right over a lawn bag and in really high gear you could have your kid crank the handle while you feed in the leafs and sticks.  I found a few plans for building your own and I've seen a few reviews for "leaf shredders" that say they stink in general as they're always getting clogged up. But it just seems stupid to fill lawn bags with all this plant material and send it away with the truck once a week and then in the spring go out and buy mulch to replace the natural mulch we all just sent away.  I get that it's not convenient to spread because it's not all chopped up into a uniform size... thus the mulcher, but I just want one less gas powered/electrical powered noise machine in the neighborhood.  I'm an old fashioned rotary blade push lawn mower and rake kinda person.  I did find one vintage shredder called a Rotocrop, but have not found a single one for sale in the whole world wide web. It's vexing.