How is showing numbers that horde outnumbers alliance in arena debunks my point which was the game is dieing as a whole (PvP) wise?
That is not what you wrote. Read your sentence again:
Read this sentence specifically “The game is dying … because of horde players not beeing able to farm resistance”. Your words not mine.
My answer just addressed your statement that horde is not playing arena. Actually the Arena participation almost exactly represents the server faction balance of PVP servers (around 40-60). The general decline of arena participation as a whole may have been connected to the general state of arena, the importance of resilience, the endless and unenjoyable bg grind and so on. But that is something that both sides have to deal with and not horde exclusively.