While your logic looks okay at a first glance, it doesn't at a second.
When a government has thousands of enraged citizens running towards the government building to set those on fire and loot them, some machine guns might be the means of choice. Though it ought to have been considered by the government du jour, what the reaction of the public will be, with the introduction of strict austerity measures, as well as jus primae noctis?
There is no fundamental reason, really, to have 1000 games opening 1000 different ports for endless protocols on a home router. Strange enough, one can invite the whole world, chat with billions of people, even tell every other citizen of this world whatsapp, and needs only http. Just to give an example.
Do not support the laziness of game coders.
A firewall that can be configured arbitrarily by user applications on their request is about the worst hack possible to connect securely to another network.