That does not make any sense at all. DBO was made in 2009 and they had games released then to now...
How does making a game, close another game?
DBO is closing because the game isn't as appealing to other games out there nor as good.
This game has glitches, bugs, barely any balance, boring to lvl up. Compared to most games this game is terrible and people play this mostly because it is a DBZ game. The game was amazing in the 55-60 cap, but 70 ruined it.
And if people don't like the idea of Private Server then don't join the PS and don't talk bad about it.