Stealing without giving credit would be a crime if it is CC 3.0-BY.
Stealing CC0 without giving credit wouldn't be a crime of course.
A solution could be that the author can give credit instructions in CC3.0 like "You don't need to credit me if you use this in a game but if you share the source then credit should be given". I don't think you should let the possibility of a few bad eggs ruin a good opportunity. It seems to work quite well in other places like OGA and unity asset store