According to askmrrobot.com the difference between the legendary helm on a fury warrior (the only difference is the 6 item levels from the helm) is about 15k dps (250k vs 235k). That is a lot but not that much of a difference. If guild has to choose between the two (with all else including skill being equal) they would likely choose the higher dps. You can still compete though because 15k less dps then another warrior is still helping your raid or other size group.
You can still compete in dps by comparing to people that don't have the legendary. There really is no problem with competition and Legendaries. Your competition hasn't been unbalanced by RNG because it has always been bound by RNG. That person could have higher artifact power through RNG. Better loot through RNG. The list goes on.
It has never been a everything equal competition and comparison when it comes to rankings. Crying about it now is silly.
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I was replying to another poster that referenced those things. More then just you has commented with things.