What's the fun of a game if you're 100% prevented from getting stronger by other nations/groups? Yes, neutral maps are there for PvP but DR is set up in a way that if a group or nations who is superior wants it, no other nations/groups can level. Say Vyseus controls WG and VD. That pretty much makes it so no one (except those that they allow to level) in the level 100-110 range can level. With the large amount o PKing, maybe the weaker nation/group can get a few kills in between sweeps and ressing but that large amount of wasted time makes them not want to invest in pills. So the other group/faction doesn't level or if they do, it's at a much much slower pace. Meanwhile the stronger group get the best leveling grounds and quickly overpower the weaker groups to a point that they really can't fight back. In the beginning this won't be very obvious but later on when one group has D2+ and the other are all CC with low tt, the gap will be noticeable.
The problem with DR is that there is no alternate place to level for CC+. Sure they can spend eternity hitting Etin... but if I'm 107 and hitting etin all day while others are blasting their hearts out in vd1, I might as well quit 'cause I'll never catch up. As for no suggestions, I've suggested putting DB or other 100+ mobs on nation only maps (but making it a limited number with reduced exp).