Deterministic is not outdated, more that RTS is outdated. All competitive RTS and RTS with good performance in large battles (2v2 or 4FFA) use lockstep deterministic simulation. Which basicallymeans Starcraft 1&2, and the command and conquer lineage.
The way to achieve deterministic with UE is to use it as a render engine only… Perform all consequential calculations using deterministic code and push the results into UE. There has been some headway in deterministic floats… im not sure if it’s been used in actual games. Usually they use fixed point.
Another option is “quasi determinism” with a dedicaded server to produce the source of truth and correction.
As for the games you mentioned. Nothing in world of tanks is deterministic. It is client server with server side authority and visibility checks. But it only has 32 units in the game. That breaks down when doing starcraft 2 style 2v2 with uowards of 200 units.