You keep saying this and it keeps being wrong. What crippled WoW PvP was not normalizing it sooner and completely, in addition to removing other pointless barriers like leveling taking such an absurdly long time for no reason.
It’s wild that you can say this with no sense of irony. Players did leave for League, and DotA, and Fortnite, and Overwatch, and HotS, and that is precisely why PvP died off in WoW. Blizzard dragged their feat for closer to two decades than one, catered to the loud minority of barely PvP players like yourself that repeated moronic platitudes like “iT’S aN MMo” and allowed the vast majority of their PvP playerbase to be siphoned away for no reason. Instead of servicing the sizeable crowd of dedicated, actual PvP players, they serviced the screeching of PvE players that weren’t going to do much more than BG once a week (if that) anyhow, but who couldn’t emotionally endure the thought of PvP being treated like PvP and not like PvE.