The attack is unique in its usage of the supply chain. The malware is not 'sophisticated' in the same way stuxnet is because it has different goals. This actors goals align with stealth above all else, which is evident in both the design of the malware and the choice of the supply chain delivery vehicle. Also realize that the network comminication scheme used attempts to blend in with the legitimate SolarWinds software. If you design a stuxnet like malware and deploy it to 18k+ companies it will be found, because exploiting zero days left and right is super noisey. This malware was minimal. It's cool in a different way