restrictions can be as basic as level or rank requirements to enter but highly unlikely as both are so easy to get these days.

Myself the ls i run dynamis with is a social ls and we normally have a whole group of 18 or more run for fun weekely to h elp the new people get wins. take all the curency sell it off so can fund other runs and all currency sold and split amongst members after. we just do it for fun. How they decide the drops from the mobs may differ to who kills it gets the drop to all currency cant be lotted on but distributed randomly or maybe just drops to who pops the nm's now and normal mobs may not drop currency at all anymore? Allowing random people to jump in and able to lot ur drops i can't see this happening i can see griefer groups mpk'ing to be idi0ts though if u can access other people's dynamis areas ... this can be a big headache but all we can do is speculate until they give us more info....

and SE is great at not being thorough on their information before release like trying to create some suspense LOL