Threats are threats, regardless of anything.
Alright, I'll go into detail. Excadrill in the sand, Adamant Nature, has 405 attack, and 275 Speed. That gets doubled in a Sandstorm, giving it exactly 550 Speed on the dot. Scarfed Froslass goes to 417 speed, and scarfed Froslass is a ridiculously fast Pokemon, with or without scarf. 550 Speed can out-speed every Pokemon, and OHKO majority of threats that would threaten it. Priority moves such as Extremespeed, Fake out, Sucker punch, quick attack, Shadow Sneak, ext. Are all not very effective, due to having the Steel-Typing. High resistance to most Pokemon's moves, and a ridiculous amount of damage, and speed, and you think that should be running rampant in OU? There was a reason why he was placed into Ubers, sure, he doesn't do as well in Ubers as majority of Pokemon out there, but that doesn't give him reason to be in OU. Garchomp with Sand Veil isn't as deadly, I honestly have no problem with it in OU.
Also, congratz, cool story bro, that doesn't make you good at Pokemon. You can have a 100% win rate, and still not be good at Pokemon. People win, people lose, all the time, and nobody has a perfect team. How often do you run Excadrill on your team outside of this League, and how often do you win outside of this League?