[ohazi]

> I don't get upset if someone opens and closes a socket to my VPS to see if something's there. My VPS is exposed to the internet.

That's not what's happening here.

My laptop is not exposed to the public internet because it's behind a firewall / NAT. This is like going to my house, plugging a device into an Ethernet port on my router, and scanning my internal network from inside my network.

Except instead of them planting a device, all they have to do is get you to navigate to their webpage. They're getting your laptop to do the port scanning for them, and in so doing, they get access to your internal network. The problem isn't port scanning, the problem is NAT busting.