Protect Your Hotspot Users
On normal networks, such as your private one, you'd want the ability to share files among other users. However, on a hotspot you probably don't want to be offering access to your files and computer to strangers. Therefore, you should block user communication on your hotspot.
If you're buying a hotspot gateway, the user-to-user traffic is probably already blocked. However, if you are configuring your own gateway, such as with a firmware replacement, you need to make sure to enable the AP or layer-2 isolation feature.