It can tell you what interfaces can reach internet:
Internet
WAN interfaces that can reach cloud.mikrotik.com using UDP protocol port 30000 can obtain this state.
That’s what many people want to know, when they do things like Advanced Routing Failover without Scripting. But Internet Detect can’t replace it, because it may give you correctly classified interface, but you can’t do anything with that.
Another thing that comes to mind is firewall rules based on interface state. It makes sense to have different rules for LAN and WAN. Problem is, Internet Detect is pretty much useless for that too, because all interfaces are initially LAN, and that’s where you’ll usually have permissive rules. So if you’d have detection on interface connected to ISP, normally it would be WAN or Internet. But attacker in ISP’s network could simply block DHCP, disconnect and reconnect cable, and the interface would become LAN. Not great. And if you enable it on internal interface, it could save you, if it somehow becomes connected to internet, but there’s no realistic way how it could ever happen, so it’s not useful there either.
I’m out of ideas, I don’t see any other use for it. So far I’ve seen it only break configs of people who accidentally enabled it.