All traffic is always routed through a proxy for everything you do.
Every bit of information you send over the internet is passed on through a whole bunch of different proxies as it is handed on from isp to isp , to get to you.
None of the game logic is done on an outside server, it's not exactly like p2p, it is p2p
One player hosts the game logic on his ps4 , acting as listen server (those two words are like a nail on a chalkboard for any gamer who'se been around multiplayer gaming on pc for long enough) , everything is sent to him, calculated on his console.
A regular consumer does not have the connection to deal with this traffic.. they will have too much packet loss (hilariously much if they are on wifi) and too much bandwidth choke to deal with it all, and the simulation is only done at the framerate the game is running on.
A good dedicated server will run the hit detection and other game logic at anywhere between 128 to 1000 times per second and equally importantly will not have routing issues like packet loss or bandwidth choke (bandwidth can't keep up so packets are put in a queue and arrive delayed)
If there are routing issues to a certain server, you and your friends quit it and pick one that works normally, and if one player has a bad connection only that player suffers, noone else does.
p2p multiplayer is always shit, some players will make less shit hosts than others, but they are all terrible.
When I play cs I do it with a ping of 6-10 on a belgian server and , with 0 choke and no packet loss
When timmy plays killzone shadowfall on his ps4 he will experience a ping anywhere from 100 to 400 ms, usually with massive amounts of packet loss, relying onprediction code as a bandaid hack to make it look like it's less laggy than it is
This is how you get shot around corners in games, get killed a second after you killed the other guy on your screen or kill eachother at the same time, how people will die a second after you stop shooting them etc etc.
Another bandaid is running more and more game logic on the client side (for example player movement/aiming direction is only tracked on the console and not on the host, so other people won't see what you see ) instead of on the server side , which is more smoke and mirrors making games less interactive and also a cause for things like getting shot around corners.
For example: the other player had the game logic for your movement ran on his own console, the movement prediction suggested you kept moving forward, he shot you, his console decided you died, the fact that you died is sent to the host/server , by now your updated position is sent to the server/host with that hilarious 100++ ms delay, but according to the server you are already dead at the other spot, so the server tells your console you just got shot and died, you are dead around the corner, he never even saw you move.
Not very interactive , is it?...
With proper netcode and dedicated servers, players send their inputs to the server and all of the player positioning, aiming, hit detection, grenade bouncing , damage taking, dying etc is simulated on the server and then sent back to every player who is connected, so everyone sees the same thing all at once and what happens is coherent with what everyone did, for everyone.
This is sent many times per second, and since the server will be receiving the updates from the clients (players) at slightly different times, you can have the simulation done even more times per second (128, 256 or even 1000) so that the server always uses the very most recent data that represents the latest frame the player saw and used inputs for, and not an older frame which would make it seem laggy) ,that is called tickrate/ update rate
With a decent ping this whole process of player input -> send to server-> calculate game logic and hit detection- > send back to player is done within less than one frame so it is awesome.
With p2p you're on a quarter of a second or more delay, with people not actually being in sync, and then there is a whole lot of smoke being blown up your ass (and a whole lot of control taken away) to convince you that it's not as laggy as it is...
The best way to imagine how this works in practice: is that on LAN or on a good server, you can imagine you and your friends each holding a toy car and moving it across the ground and slamming them in to eachother.
With peer2peer multiplayer noone gets to actually hold the toy cars, they drive themselves and everyone can give it a poke in the direction they want once a second. You don't actually get much input and there isn't much moment to moment interactivity as you are at the mercy of where the cars decide to go between pokes.
Oh and each player has to close their eyes for a moment at different times so they can't all see where the other player's car actually is at the same time as the other players.
This is why dedis are such a big deal, why people were rightfully outraged at mw2 releasing with no dedis on pc, why a lot of people don't like bf3 infantry combat (dice's servers aren't very good and their netcode is pathetic) , or why people hate the matchmaking in cs: go, because despite the matchmaking actually using dedicated servers ran by valve, those servers only have a tickrate of 64... so the hit detection isn't consistent.
Communities benifit from having control over the servers, so they can hire from whatever host company that provides them with a solid no packet loss route to their and their friend's homes.
With bf3 and cs go matchmaking you are at the mercy of w/e ea and valve picked.
Xbox one moving to all dedis IS a good thing (though about as praiseworthy as someone flushing after they take a shit, thanks for not stinking up the house and making the only right choice there is? something that's been standard for a long time everywhere else? )
Again , you will be at the mercy of the servers being any good, ,but even a bad dedi is better than the best p2p connection.
And the stupid PR spin of calling the servers that handle the matchmaking and rank ups (the same servers that exist for every p2p game...) for killzone SF dedicated servers is insulting, so please don't fall for it.
