Leaf blowers could do what boat motors have been mostly forced to do and switch over to four-stroke motors. Motors have emission standards to follow. Battery manufacturers has environment laws to follow and if they produce products that fall below the minimum standard then they have to improve their product or be banned from selling their products.

Edit: I'm not authoritative, but I can't think off the top of my head of any rare earth metals that an electric leaf blower uses except perhaps in the batteries. But also, there are plug in electric leaf blowers.