Five tournaments have already been held in the "only X" format, and more will be held in the future, so there is no need to change it without a good reason.
You will be able to play Necropolis against other factions in other tournaments.
There is a good reason. Necropolis is the only faction in HotA where there are no clearly defined strong starting heroes (due to Galtran leaving). In games where Necropolis plays against Necropolis, the red player will always have a significant advantage. Perhaps it would be necessary to introduce the possibility of banning one hero, as is done when playing a mirror match.
