Or because it's not that basic and any solution that isn't 'you stay in place until you reconnect or X minutes pass, the instance keeps on going, if a patrol or AOE kills you, oh well' would be very easy to exploit given the design of Deep Dungeons (aside from the 'snapshot' suggestion, but that's unrealistic for technical reasons).

Mind you, staying in place would be better than the current status quo where a disconnect is an immediate eject, but it's also not what most of the suggestions are proposing.