I read one reason is because they are difficult to disinfect so you could potentially spread disease/evasive species from one body of water to another. That might be the only reason.
So far looks like only these places have banned them:
Maryland.
Alaska.
Missouri.
Nebraska.
Rhode Island.
South Dakota.
Yellowstone National Park.
I’m in N.Y....still legal last I checked.. but yes..environmental concerns...could always go with rubber soles and use strap on cleats..here in upstate NY we just call them all korkers...good for ice and slippery rocks..an actual pair of Korkers brand will cost a little more but are of good quality