We're talking about anti-lead right ? So yeah, Tar anti-lead always wear a sash, your battles doesnt matter and refering some arguments to the ladder is p.bad since there is very few people who play seriously on it (charizard, props to you).
Pokemon faster than him who can take 2 hit arent a true lead anymore so Tar did his job (and there is really no lead able to do that beside Groudon who invest like a crazy in speed). Also, there is really a few mons able to do that. Tar was in DP, and still in BW, the best anti-lead you can have. Anyway, that was off topic.
The skill level of the average ladderer does not matter. The fact is, there is only
one instance in which I have actually
seen someone using a Focus Sash Tyranitar (lead, anti-lead or not) out of the countless battles I've had on numerous ladders across multiple servers. As such, I have every reason to
not believe in the claim that "Tar anti-lead always wear a sash". Maybe
you believe that an anti-lead Tyranitar at the hands of a skilled trainer
should always wear a Focus Sash, but that doesn't change the reality that Focus Sash Tyranitar
is almost non-existent on any ladder, and therefore, until a significant number of people start actually using Focus Sash Tyranitar on the ladder, Focus Blast on anti-lead Kyurem-W is perfectly viable.
Similarly, we all know that Arceus is the best Pokémon in the game and every team should be able to handle it. But if, hypothetically, for some reasons no one decided to use Arceus on the ladder in spite of that, then a team that cannot handle Arceus would actually be viable on the ladder. It is the exact same story here.
Kyogre, a very common lead, easily outruns Tyranitar and takes it out with two hits, while surviving any of Tyranitar's attacks barring a critical hit. Same with Groudon and Aura Sphere Dialga. But the main reason why I do not think Tyranitar is anywhere near as good as Kyurem-W as an anti-lead is because unlike the latter, the former cannot take down Dialga, Groudon and Forretress before they get Stealth Rock up. And if they do, they have pretty much already completed one of their major duties anyway. Being able to prevent the opponent's lead from setting up Stealth Rock by being able to KO them before they can use that move is a huge part of an excellent anti-lead.