Is reaching relic 7 even worth it?

So I find this particular issue to be very frustrating. Call me a newb but is it really worth the trouble of fully relicing a toon? Sure mods make all the difference because by the end of the day everyone who has an ot chewie at gear 13 and relic 7 fully Zeta'd will have a toon with identical stats. But when it comes to certain areas of the game namely any event that doesnt involve player vs player, one would think that having a team of powerful toons at relic 7 would almost ensure victory due to the sheer amount of power each individual toon has as well as the best synergy to really unleash a squads full potential. Sure mods are essential for additional speed and stats like potency and tenacity, it just seems off that a fully developed team cant be nearly guaranteed victory. A good example of this is the level of difficulty with the Darth sidious phase of the dark side assault battle. I've recently got all but 2 of my nightsisters up to gear 13 and between relic 2 and 4 with the final 2 being gear 12. All Zetas are filled, best suited mods are equipped to the necessary toons and though I have yet to try the sidious phase on the second to last tier (the one that rewards zeta and gear 12 finishers) I've heard that he is absolutely near impossible to hit since he opens with an aoe attack that instantly obliterates the team regardless. So is it really worth the wasted resources to reach relic 7 if it means nothing?