There's a huge (literally) difference between wide road tires (that some would call "fat") and fat bike tires. I've seen some of those e-fatbikes (on the bike trails where they have no business being, since every one I've seen has been a Class 2 throttle bike, and they're not allowed on bike trails) and have no idea why people are riding them there. On snow and sand, yes, they are very much in their element and nothing else comes close. But on pavement, what's the point? No one in this discussion has been advocating in favor of fatbike tires, it's been about wide vs narrow road tires. In an ebike context, I'd call 28-32 narrow, 38-48 wide.