You may have misunderstood what I mean when I use the term "publicly reachable". It is not only the static nature of the IP address that make it more suitable

You may have misunderstood what I mean when I use the term "publicly reachable". It is not only the static nature of the IP address that make it more suitable for peer-to-peer. It is the ability to accept unsolicited inbound connections on any port. The key word is "unsolicited". Essentially, the user pays extra for the "privilege" of less stringent firewall rules.