Think of the asphalt as if it were glass. The alligator cracking problem is caused because the asphalt has been broken all the way down to the base. You can't fix it by putting a skim coat over it. The cracks will just come back. You have to cut out and remove the broken asphalt all the way to where it isn't broken and then patch the spot with new asphalt and roll it. What they are doing is like spray painting over broken glass or rust. It's lipstick on a pig.