I don't know the spec of the cards but the 6900xt was even faster in some games than the 3090, now the 7900xt "successor" doesn't even get close to the 4090 at anything.

Because not much has changed since original Vega. AMD is still almost one tier behind Nvidia. The only reason why AMD could compete with full GA102, was because they had a node advantage that gave them frequency scaling.

Imagine if Ampere had been on TSMC, and clocked 10-20% higher. Then suddenly the 6900XT would have been sitting somewhere around the 3080 10GB on a good day. And the 6950XT might have eeked out a win vs extremely cut down GA102. But the 3090/3090 Ti would have been far off into the distance and completely untouchable.

It would also have meant the 6800, would have had trouble outperforming a full GA104 card. 6700XT would have been behind 3060 Ti almost always.