Many players went out and assised a lot of player on the first few days to earn a lots of rewards.
Each time a boss you have hit is kill you get closer to the "wall".
Result: they got to the 8.7M wall very fast and with very few EP.
If a player just kill his own bosses alone he might get as much as 1,000,000 EP without getting a single 8.7M boss.
Maybe it better for players who cant handle 8.7 M bosses not to rush to the wall but to proside slowly and collect as many EP as posible on the way.