That is where you are wrong. There's a reason Sand is beating rain in terms of usage. Sure, abusing a weather is really nice, but it allows for more creative team building and unique strategies that other weathers don't really bring. Sun is EXTREMELY predictable, rain isn't that far behind. Everyone knows that a Venusaur on a sun team translates to a Growth sweeper, and Keldeo on a rain team translates to a Choice Scarfer or Specs most likely. Sand and Hail have little going for it abusing wise, but strategy wise, they have quite a number of creative options. Hail is just hard in general, but it gives you a challenge. You wouldn't want to win this tournament easily now would you? I hope not. That's why I'm using hail as my weather of choice for the winners bracket over sun. I will feel a great sense of accomplishment if I win, and I've had much more freedom, seeing as I don't really having to worry about weakened Water-type attacks or making sure that I win the weather war so Venusaur isn't entirely useless. Hail for my team is more strategic then abusive. Sure, I can spam Blizzard in hail, but that's about as far as it goes abusing-wise. Hail acts as more of a residual damage that works really well in conjunction with Toxic and Stealth Rock, and it's really nice for the almost KOs that you would normally miss out on if hail wasn't on the field.
So yeah, use your underdog weathers to your advantage, and worry less about abusing it and more about being creative with it :)