And using the "I've never played showdown in 1 year and went 4-1" as a reason to show it's not competitive is bullshit imo.. The easily accessable showdown.. Literally make a team in a few minutes and play pretty much instantly can give any noddy a fairly decent chance to get practice in and perform well, especially if you've played PokeMMO tiers throughout, the transition really isn't that hard.
I don't know what the outcome of the original vote was but even if only 20% of the voters wanted showdown, that's a large portion of interest and comparing that to PokeMMO tiers, it's probably similar. I've managed teams a few times and finding people back then for tiers like NU, UU or Doubles was no easier than finding a good showdown player.
Voting against showdown just because you don't play it is not a good reason to reject it, however, if you don't enjoy it or believe PSL should be strictly PokeMMO tiers despite it being here since the start, then fair enough.