Ok, so the current problem and explanation for needing premium for private lobbies it is that on matter the number of players in it it takes a whole dedicated server as Russ says.
With my limited understanding of this engine and networking in general could this be interpreted as: the main server creates a map with x players and manages it? Also as I understand as in some other online games that allow player hotdrops , that is join an already started game late, mainly FPS games, so couldn't MWO do this too?
With these two thing it should be plain where I'm going with this, create a few maps with several separated arenas , so a map ( a single map , yes limiting but for free

and size of each arena would scale with group size ) with 12 arenas for 1v1, 6 for 2v2 and 3 for 4v4 , where you drop in at any point , have a fight and after one team is dead ( yeah, there would be quite a number of teams... mby each would have a different color, or not, not sure of the limitations ) they get a score board and exit and there wreckages disappear freeing the arena in the map. if there are more teams of any size than the map can hold a new map is created, this means that at any point only 1 of each maps exists without a max number of players, and having 3 dedicated servers not filled with 24 for free doesn't seem unreasonable.
Edited by Nik Reaper, 29 January 2016 - 08:16 PM.