just like what oteldoudou said:
Well, I don't agree on the time thing
I just had over the week end a loooong party in Ruins, and we played for a couple of hours (once reached 200, it starts to be very long levelling up), while none was AFK in the party. We were just chatting and joking around.
Now, if we woule had have to go back to a NPC at entrance every 30 minutes or so (and you know how ruins if huge), and then coming back to see that another party have taken your spot... no thanks.
So against botters, sure, but not with a time limit