There's a lot of reasons why this is cool, but I'm skeptical about it's aims to get rid of kerosene lamps. Kerosene lamps are made with garbage. They can be replaced in minutes if there's a problem. Fuel costs are high, yes, but capital costs and maintenance are low. Those matter. To really make this a long term win, you need to make it indestructible and easy to repair with on-hand parts. I hope they can do that.
I can see that potentially being a problem, especially if dirt or something gets caught in it. However, the most delicate part of it is the most replaceable, that band could be easily made out of cloth or leather, and motors are usually fairly available. It's most certainly a better argument than "it's not much power" etc, but I'm not convinced it matters too much. I doubt just as much as the next guy these things will change the world, but it's a noble idea and a noble purpose.