It's honestly somewhat baffling to me that folks will choose Rust for gamedev right now. The state of the open sourced tools are just not there yet, especially when compared to Godot, and at the same time these games are running on PC hardware which tends to get faster every year.
Also for ECS... one thing I tended to realize is that when developing a game, pigeonholing everything into an ECS can seriously tend to get in the way. A lot of (efficiently written) game code is best handled in an infrequent event-driven way.
An ECS backed game engine like Bevy can make big mobs more efficient, but few games will actually leverage this effectively for fun gameplay and at the same time modern PCs are fast as hell.
I think about Starcraft from 1998, created when virtually all PCs only had one core, and its 200 unit per faction cap. Blizzard hasn't increased this cap because it doesn't necessarily make the game more fun. Now should a gamedev today, 26 years later, making a 2d isometric game for the PC be worried about performant multithreading????