How much does optimal DPS depend on good RNG? (Crits, DH)

[Undeadfire]

What I mean is back then for example the difference between say a 95th percentile player and a 90th percentile player was often attribute to rng, latency, or just sheer luck.

Actually it's 95-100, 90-95 is never rng in a logrun, you will always hit Orange (95-98) usually with good enough skill.

You could usually ignore the 100th percentiles as often they are abnormal runs where one player is heavily padded... (single balance vs aoe balance for example)

This exploit was fixed in with the rDPS math calculation and only leaderboards list rDPS as a main comparison. rDPS calculates your DPS without outside buffs except yours. Each job has their own optimal kill times, and a strategy requiring a DPS to do it would usually be subbed out to keep the log high.

This was on an individual level at least as things like compositions and the luck element of things like ast cards also had a huge impact.

It is individual yes, but like I said fflogs no longer mainly calculates this.

I would hypothesize that with the advent of direct hits. That percentage could be even bigger now as its an extra layer of rng

It got more RNG since DH got introduced, you spam the runs till DH/Crit trigger on your bursts, not the downtime/auto attacks.