Steaming updates?

Today we were all asked to leave the game and restart it for an update. All information about GW tells me updates come without patches, streaming when we are playing. We should not even notice it. Is this information wrong?

That's for zone and content updates I believe. Normal client updates will require a restart, though I was able to continue playing for a couple of hours after the patch went live...

Actually it took only a few minutes to restart and dl the necessary files ! I only was confused and when it happened at first I thought it was a scam because there should be no patches lol. So I did not leave at once.

Usually you can still continue doing what you were doing or what you wanted to do, but when time passes you may notice that there are less and less other people around.
Only people who use the same build of the game can see each other/play with each other, so it could happen that you stand all alone in Ascalon City District 1 although you know that hundreds of other players are there at the same time - you just can't see them, talk to them or interact with them.