Even Nadia would concede that Simone’s routines are an order of magnitude more difficult than anything she did back in the 70’s. Nadia pushed the limits of her time, but 1976 Nadia wouldn’t even sniff a medal today. Nadia was the best of her generation, and in 1976, maybe the best of all time. But gymnastics has evolved into a different sport. No longer is “smooth, fluid and graceful” critical to scoring. Instead, it’s strength, athleticism, complexity, and incredible acrobatic feats. Note that Biles’ beam dismount, a move that she is currently the only person capable of performing really well, and is thus named “the Biles” was downgraded in scoring standards to discourage other gymnasts from attempting it due to injury risk. Many, if not most people consider Simone Biles the GOAT, but comparing her to Nadia is difficult considering they effectively competed in different sports.
A lot of this has to do with training also. A lot has been learned since 1976, and Nadia today would benefit from that as well. She may fare a lot better than you think.
That came with the Chinese gymnasts, once they rose to prominence.