I guess they antagonize anyone that has moderate exposure using their IP

In some countries copyright law says that if you let people use your copyrighted material with little to no impediment then you cannot suddenly request whoever is using your material to stop

Let's say that Nintendo allows fans to make fan made Mario games for 5 years. Then they suddenly sue everyone and say "hey you have to pay for copyright or shutdown". A judge can decide that since they didn't enforce their copyright for some time they cannot sue people that are using their IP.

From a legal perspective the act of policing your own copyrighted material is the company's responsibility. This law prevents companies from relaxing their copyright claims for years (essentially allowing people to use it) and then suing everyone for using their IP. In other words Just let everyone use it, then sue them. The law is there to prevent that

Nintendo is likely super strict because "let people use your copyrighted material with little to no impediment" has room for interpretation in a court room. So they go to the conservative side and shut down everyone. Also consider that they're right next to China. The piracy capital of the world. It's not a surprise they're scared about their copyright.

I'm not saying that what they're doing is right. It's not. But I see where it comes from.