Datacron Set 4 + Feedback Response Information [MEGA]

That's not what the high-end meta was like at all. People would see what countered their defenses and adjust. There were LV comps that made SLK far from guaranteed. Same for the BH counter. There were Rey comps that made SK super risky but still doable.

Now, with DCs, things are more as you described. Rey can be 100% immune to SK counter. JML can 100% counter JMK.

I think you have it backwards when it comes to counters and their viability.