It really doesn’t though. I’ll try to explain the math for you:
Let x equal the % of groups that premade when the queue is < 1 min.
Let y equal the % of groups that premade when the queue is > 1 hour.
For alliance, the amount of premades they were facing before the changes was equal to y. After the change it is equal to x.
For horde, the amount of premades they were facing before the changes was equal to x. After the change it is still equal to x. The only thing that changes for horde is it that they are participating it more premades, but they don’t actually face more.