Since there seems to be some confusion when it comes to data used for balancing:

90+ or 95+ percentile is used to see what the balance between classes is like, and to make adjustments, because at those high percentiles each class' kit is used to their fullest potential and gives us an idea what kind of DPS a class can conceivably put out, there's not much value in looking at low parses because there these kits are not fully utilized, and in some cases some skills are used wrong, or not used at all.

And I would argue that high percentile does matter during progression, because while you may cancel a cast or miss a GCD otherwise to focus more on mechanics, you'll still be trying to use your tools the best you can, especially after seeing a mechanic a few times.