honestly, there IS no good reason. it’s become convoluted and silly, but being kept simply for foolish principle.
honestly, they COULD integrate cross-fact LFG and LFR with little ‘canonical’ issue, as these are technicly sidestories, and we see canonicly where some on both sides help each other out. it would do nothing to dull the faction divide since its ‘off the record’ as it were, and more for gameplay grouping availability than story anyway.
as for the ‘cant talk to each other’ crap, thats NEVER made sense to me. its clear there is a common tongue of some sort.