The power differentials in WoW are a lot bigger than 2%. I would wager that less than 90% of the players even are LFR geared, but assume a casual player with a mix of LFR gear, crafted, legendary, heroic BoEs is probably sitting around ilvl 663. Depending on their spec and the fight and playing well they are probably doing 30k DPS [0]. Someone in full mythic 4p (ivl 700+) is going to be doing 55-60k+. [1]

These numbers aren't going to be a perfect comparison because of fight length, strategy changes when you overgear content, skill differentials, etc but gear is pretty important.

One could easily argue that having the highest end gear does not really serve a purpose if you aren't doing any actual raiding or PvP though.

edit: I should probably mention that the last expansion (released last November) did a massive stat squish. In the last tier, t16, an LFR geared player would be doing 30k (ilvl 496ish), 100k (ilvl 528-540), and 1.0m+ (mythic/580+). Player power was increasing so much they had to start working around not being able to increase raid boss HP higher than 2^31 - 1. 25 man heroic Thok had ~2b HP for example.

[0] https://www.warcraftlogs.com/rankings/7#bracket=2&difficulty...

[1] https://www.warcraftlogs.com/rankings/7#bracket=7&difficulty...