It takes one motivated proactive player to form a Horde community. Others will join. There’s Horde out there that enjoy War Mode WPvP, that’s for sure - this is aimed at those Horde.
Some will join via forum recruitment posts, and LfG is a great recruitment tool + group padder.
There is no shortage of activities for a WPvP guild or community - with different levels of difficulty because of sharding and/or numbers required. LfG padding might be desired (or not) for a smaller community.