Why do servers going down cost us maps?

Canadian server kicked me off and I switched to American server after a few tries failed logging back into Canadian, and it worked but the map I was DCd from when the server went down, was gone.

Game clearly tracks map progress as it knows where you were when you leave a map and come back in, even after logging or killing the client, so why does a server going down make me lose 100% progress and all events that were in that map?

Is it temp memory on the server and if it goes down it loses all that info?