99th percentile is unhelpful for a number of reasons. A lot of it (especially this expansion) is crit RNG, due to how damage is so compacted into 2 minute bursts with high potency hits. There's also the problem with feeding- usually when someone's that high, it's because they want to be. So the run was catered to them. Uptime may have been bent around that person. Strategies may have been tweaked to make sure that one player had as much padding as possible. If it's a buff-dispenser job, you can ensure the rest of the party is high personal damage so their percentage buffs have magnified output, increasing that player's rDPS.

Now, looking at the specific actions that person did during their run is definitely helpful if you're looking for optimization tips. But if you go in expecting to get above purple or low orange on that alone, you're not gonna have a good time.