The iPad's biggest drawback for gaming (for me) is not it's horsepower but it's form factor. It's just too small to be immersive no matter how good the graphics are. It's not a device you can really play together on i.e. 2 people side by side.
Granted the Nintendo Switch screen is smaller but you hold it with both hands, that is tough with the iPad - you have to use a controller with it then it becomes a screen not a hand held device.