My thoughts are that it is a "safety" device, to keep you from putting your hand into the chute area to clear it. Should the chute and impeller get clogged with slush, it is possible that the impeller could turn suddenly when the clog was released, and if your hand / fingers are anywhere near the impeller, serious injury can occur. When I was an EMT on the rescue squad, we saw snow blower injuries frequently, and many were hand injuries. I always turn off the machine, before going anywhere near the snow blower. I also use a plastic shovel to clear any clogs. The tool to clear the chute is commonly called "Chute Clearing Tool" or "Snow Thrower Cleanout Tool". They range in price from $14 to $20 on average at your local small engine store.