I can't say why top guilds do what they do. For challenge? Glory?
I would suspect they like to be the first to do a thing.
I would suspect they like to perform at the highest level.
They couldn't do the strict 10-man raiding currently because they had to focus on 25-man. They couldn't be the first if they wasted time on side projects.
And are you performing at the highest level wearing subpar gear?
Would Paragon or Ensidia beat Phoenicis or From Chaos if they made it their goal to focus on 10-man strict raiding?
League of Legends is rigged
9 hours ago