As proof of your hypothesis, I am offering the PvP experience in Elder Scrolls Online. So-called “ball groups” dominate. Ball group members all agree to wear armor sets that boost the other members of the group and are complimentary with other armor sets worn by fellow members.

These group-focused armor sets mean that individual members are weaker alone than players wearing armor sets which enhance individual performance. But a ball group can take down groups several times their size if the other groups are composed of players with only individual enhancing armor sets.