Yeah I know what you mean, but I believe they can (at least on pc) tell the difference between lost connection and manually quit. If Origin is still online and running, that means the player is still online and not unplugged, and by saying "manually quit" I mean executing in-game commands like "quit" or "disconnect", which should be clear messages to their server.
I think there're lots of other devs using the "If no respond then drop connection" method, but I don't remember many of their games as frustrating as EA's.
Well you can tell when they click the quit button, just not the differences between any different kind of actual disconnects.
My understanding is that the EA server is extremely strict about dropping your connection. Most servers will drop it after a set amount of time, but the EA one seems to be a very short amount of time so a couple of missed packets(which isn't terribly uncommon) can result in a disconnect.
By comparison I remember tricking the old Diablo 2 servers by pulling out my cable and plugging it back later so I could get 2 PCs using the same cd-key online, and it let me re-establish the connection. I could keep the cable unplugged for a good 5 minutes before I got kicked back to the menu.
The EA server is like 2 seconds.