I can only speak from my limited experience working in Unreal but a fairly robust career in audio. It seems to me that the new audio approach is also trying to cater more for procedural approaches and that control buses can be used as “faders/tracks” for individual “instruments” that can then be grouped and mixed into Control bus mixes. The soundclasses and sound mixes can then be used to mix and control a number of different CB mixes. The analogy in mixing would be tracks grouped into aux returns (CB ->CBmix) and those track and return levels controlled by VCA faders (soundclass ->soundclass mix). Both the CBmixes and SCmixes can then be used as “snapshots” to quickly jump between mix states. Snapshot mixing is very common in live sound (FOH/monitor mixing) and post. Just my 2 cents.