DPS display could easily be solved with a system already in game.

[Vire]

That actually depends on the content at hand. The hardest raids do often gain the absolute most amount of benefit from parsers. Raiding requirements don't always involve parsing though. Source: over 10 years of raiding in games since FFXI and vanilla WoW, before parsers were even a thing. Our work-around was knowing where we could gear up to meet unknown requirements to complete (and this worked fine when you hit that point).

I can say for a fact that every Vanilla Wow guild competing for world first clears of AQ and Nax where using dps parsers. Specially so for every guild who was in the race on Korgath at the time. I don't know about FFXI because I never played the end game seriously. But that is disingenuous saying vanilla wow raiders were not using parsers/ dps meters. They where a thing since the second boss of BWL was a dps check enrage fight.