Map drop restriction in party?

I just did my first couple maps with a friend and it seemed like only the person which opened the map through the map device was able to obtain maps through drops (with permanent allocation). So i wanted to ask if there was such a 'restriction' to the drop and why?
thanks!

There is such a restriction. It is in place to allow mapping with strangers to be possible. If maps were allocated randomly like other items, then mapping in a party would be impossible to sustain unless the players in the party were sharing maps.

thanks for the awnser!