I'm a gameplay engineer who worked on THE FINALS. There's a GDC talk that one of the engineers who worked on the destruction system gave and I imagine that talk will be uploaded on youtube at some point in the future: https://schedule.gdconf.com/session/engineering-mayhem-techn...
Most of the answer to your question is really good iterative tooling on the authoring side, and very pinpoint optimizations on the runtime side. You basically amortize everything, how much is "strain" is simulated per frame, how much physics simulation is simulated per frame, how much is replicated per frame, etc. Almost any game could do what THE FINALS did but it really just requires you to solve many of the hard obvious problems for a good couple years.
I'm glad you enjoy the game! I also agree with you that there's a lot that can be improved.
Most of the answer to your question is really good iterative tooling on the authoring side, and very pinpoint optimizations on the runtime side. You basically amortize everything, how much is "strain" is simulated per frame, how much physics simulation is simulated per frame, how much is replicated per frame, etc. Almost any game could do what THE FINALS did but it really just requires you to solve many of the hard obvious problems for a good couple years.
I'm glad you enjoy the game! I also agree with you that there's a lot that can be improved.