Certain games require multi- architecture floating point determinism to work well.
That’s especially true for games that work best with lockstep or rollback netcodes, e.g. RTS games, Fighting games.
Right now, UE5 can achieve determinism, but only across certain groups of machines, as some FPUs do different stuff to improve performance with floating point operations (e.g. weird optimizations for three-or-more-values-at-once operations, trigonometry etc.) that are not described by IEEE 754 standard.
To achieve full floating point determinism that would yield perfectly same results across many processor architectures and build configurations, some devs would like to sacrifice performance.
What I’m talking about is an option for the engine/its gameplay related parts to use soft floats instead of hard floats.
Without an option like that, every studio that chose UE5 to make an Lockstep RTS or a Rollback netcode Fighter would need to write every already existing feature needed (pathfinding, character movement, perhaps even lower-level stuff like physics?) from scratch to fit their needs…
…Or they would need to fit to UE5’s networking framework which is either suboptimal or problem-generating in their case.