The fleshing knife is an actual necessity in the fur industry. If you run or work in a fur shed, this tool will save time and frustration. However, if you are experienced and you end up with an emergency, you can always use other tools for certain animals.
For example, minks, weasels, and muskrats can be done with butter knives as well. Small pelt scrapers will also get the job done. Such tools are not necessarily helpful for large animals like foxes or coyotes though.