If I'm playing poker I can't just leave while we are dealing and take my chips with me.

Yeah, I'm not sure how this is an apt comparison and misses my clear statement of 'the ramifications should be presupposed'. I can't off the top of my head name what happens in this scenario in a normal poker tournament, but I imagine its accounted for and I'm not sure what the equivalent to 'chips' would be in an EDH pod, money you've bet on it perhaps?

This is again the issue, who cares if someone is using it as a special action to concede at instant speed to shape the outcome of the game; if its an actual issue to be resolved there are better ways to establish protocols for that which might make it a less negatively impactful action for everyone at the table without taking the right to do so away from people who just really want to scoop and not play out three turns they're loosing during.