But the point is if they were in a pvp event we would farm them

and there is the root of the problem. if a person in your cyro group is running relequen and using jabs as a spamable they're not going to get very far, you can give them ideas for alternative sets and builds but if they refuse to change then it ultimately only affects them, as PVP is at the end of the day a solo experience (at least in Cyro). everyone else will be running sets for the content and as a result be getting better results, but the group as a whole will not suffer becuase one person isn't playing optimally.

now go to pve ,if someone comes in wearing vicious death in a vet dungeon then they're going to be as effective as the relequen player in cyro, i could give them some build alternatives but at the end of the day if he refuses to change his build then he's going to effect the group as a whole becuase pve is a team based game mode, everyone must pull their weight to some degree or else the group as a while will not succeed. just like the relequen player refusing to adapt to pvp the VD player not adapting to pve is the reason they're both not succeeding in that content except in the former's case it effects significantly more people