True as far as it goes. Modern GC can mostly be done concurrently (it's only heap compaction that requires stopping the world). Fully pauseless GC is very much possible (see e.g. Azul C4), as are e.g. architectures involving multiple short-lived processes with individual heaps. Even without that, it's often possible to do a relatively small amount of manual work to do the things that require pausing only at appropriate times.
C4 is absolutely a production product. It's used in systems that insane amounts of money depend on. As for the manual approach, I've seen it work in production.
It's not just the pauses though. Cities Skyline has terrible performance, far worse than other more-intensive 3D games, and I can't help but feel that their choice of game engine is a major reason behind that.
