Lets try to explain what the OP is saying, in different words/examples.
(Since I have to go through the same thing as the OP)
If I pull my plug out, the game waits like 30 seconds or more, before it will say I have been disconnected.
In that period of time I can move around, and try to use abilities, but nothing happens, and i dont see players moving.
(This is how I know I get a true DC, not SE trying to DC me)
If I zone, Get moved through teleports, including raises, or someone leaves an instanced dungeon, leaving the group, I get DCed roughly 10% of the time.
But when I try to log back in, it says "You're still in the game"
That message only shows up, when your client kicks you from the game, but the servers think you're still on them.
Your client is incorrect, as you havnt lost connection, you can literally use an ability, see its effect, and see someone type messages none stop, all the way up till that black screen kick.
There was no actual disconnection, just the game THINKING there is, because of a small packet loss, at a weird time.
(This is ignoring needing the game to be more client side for certain things, like the mount, dodging AoEs, etc)
Just the idea of being kicked when "moving locations" isn't even an issue about client side, so much as its programmed to go into a panic, and kicks you over 1 lost packet.
(Technically there's more to it than that, because I can also not lose packets, and get kicked as well from zoning. I even have 2 versions of the game running on my same/single PC when my friend is over, he uses a controller, while i use a keyboard. We can both zone at the same time, but only one of us is being kicked, despite our connection being the same.)
The game is programmed to improperly handle the situation.
Other MMOs dont do this, so obviously they are doing something wrong. (Yes, I understand that the game servers are in a different location and go through different routes. Even so, the same issue happened in the prior server locations, when i was right next to them. Single packet loss, leads to a kick. Other MMos say "hey, l;ets wait 30+ seconds, and see if they come back from what we think is a DC".)