A fat bike is a bike with >3.8" tires and is not necessarily an e-bike nor an issue. Some people use them in the snow, sand or trail without issues to anyone and I have occasionally also used mine in the city because it was more comfortable to ride at slow speed than my road bike and stops on a dime thanks to the available grip.

There are a number of trendy aliexpress quality e-bikes that are also using fat tires and are ridden by idiots but the problem is not fat bikes per se. The problem is idiots on unrestricted/modded e-bikes. Ban fat bikes and they will use unrestricted e-bikes with different tires and the problem will be the same.