The gear issue is minor, RR is still the OP part.
Opportunist IV it is +14% crit.
BiS gear is 16% crit.
Comparing Vanq with Sov straight up it is 1% crit that differs.
As soon as you hit Vanq level of gear you are more or less competitive gear wise. What you lack is 25 RR, those 25 RR lets you get 11% more parry or dodge/disrupt and e.g. 5% reduced CTBC from FS.
It's possible yes that the RR may be more responsible than gear for gap between rank 40 players
