Originally Posted by
Endus
Those would be people who are better-geared than most, at the time you're talking. Once everyone is geared up, damage will vary by a good 3-5% or so, depending on the spec in question, and that's absolutely a broad enough range to allow for RNG's influence to rise to the fore.
In the early stages of content, the same names dominate, because they're in the top guilds gearing up faster, and thus have a gear advantage over the majority. Near the end, it isn't nearly as true.