It is rare in WWW land, but not rare in P2P land. Note: this is a simplified explanation. Some details are glossed-over/wrong. But it will give you the basic

It is rare in WWW land, but not rare in P2P land. Note: this is a simplified explanation. Some details are glossed-over/wrong. But it will give you the basic idea. In order for someone to be able to talk to your machine they need to know your IP address. In general, this if fine because you can just tell people your IP address. However if you are on an internal LAN then you have the same external IP address as everybody else on the LAN. There needs to be a way to route packets to you. A P2P application needs to have some way of telling the outside world, "If you want to send packets to me, this is how to do it". Of course, LANs are designed to stop people from being able to randomly send packets from outside the LAN to machines inside the LAN for obvious security reasons. So if you do this, then you are compromising the security of your LAN to a certain degree. As I said, P2P apps need the ability to advertise how to connect to you or else you can only connect outwards. In other words, if it were a telephone, you could make outgoing calls, but couldn't receive incoming calls because nobody knows where you are. So when you start up Skype or Bittorrent, etc, it usually uses some tricks to figure out how people can contact you and advertises it. The problem with WebRTC is not so much that it has this capability -- it needs it. The problem is that it is accessible remotely and doesn't ask for permission. You can go to a website that will jam some javascript at you that gets this information. You can't even turn it off in the case that you don't want to use WebRTC. Requests to change the functionality to prompt the user (or at least have an option to prompt the user) when this functionality is used has been turned down. Not a lot of coherent reasoning has been given (as far as I can tell), but I imagine that the implementation is difficult and they don't think the majority of users will care. I suppose as a middle-ground they have offered this plugin. I have my own strongly held beliefs on this topic (which may be evident from what I wrote), but hopefully this is neutral enough that you can understand the issue, do some reading and form your own opinion.