I hear your frustration. They did change the rules mid-stream, and it's affecting a great many people. But if you were beating people with many more relic tiers than you, you've got skills. Remember that the difference at 1-2 relic tiers is quite minimal. If you were beating ppl under the old system, you can beat them under the new system with fewer relic tiers as long as you're within that crucial range.
Strategic investment of signal data and joining a guild with good raid performance (if you're not already in one) can get you over this hump in a few months.
I've had to change my relic investment plans pretty drastically myself. It's not fun, to retweak all the relic tiers on these toons you already felt you had dialed-in for power level, and I fully support you making your decisions on which games to play based on which ones are fun to you. But I'm confident that if you stick with it, you'll get back to a new equilibrium soon.
Good luck whatever you decide.