Well, GC latencies don't bother game developers who work with Unity or people using Java or C# for high speed trading.
Realistically, having the option to use a GC is a boon for many applications. Not everything is hard realtime all the time. Some complex applications tend to have a hard realtime part and parts where it doesn't matter. E.g. a CNC machine controller does not need a guaranteed response time for the HMI or G code parser. But it needs to have a tight control loop for the tool movement.
D is a language where the GC is default, but optional. And the compiler can give you a guarantee that code that explicitly opts out does not interact with the GC and -importantly - can't trigger a GC run that way. However, as this was an afterthought, parts of the language need to be disabled when opting out and not a lot of library functionality works with that.
GC latencies doesn't bother them, because they put large efforts into ensuring there is not garbage to collect. Tricks normally reserved for hard real time embedded systems like allocating all memory buffers at startup time.
GC is very useful for programs that don't have any form of real time - but games are real time and thus you need to be careful to ensure that the worst case of the garbage collector doesn't harm you. Reference counted garbage collection gives you this easier than the other means. Note that I said worst case - the average case of garbage collection is better in most garbage collected languages.
I have never seen such memory mamagement tricks employed in Unity scripts. I'm not saying that they don't exist. They are only rarely required. To be honest, I expected things to be much worse from previous experiences.
Realistically, having the option to use a GC is a boon for many applications. Not everything is hard realtime all the time. Some complex applications tend to have a hard realtime part and parts where it doesn't matter. E.g. a CNC machine controller does not need a guaranteed response time for the HMI or G code parser. But it needs to have a tight control loop for the tool movement.
D is a language where the GC is default, but optional. And the compiler can give you a guarantee that code that explicitly opts out does not interact with the GC and -importantly - can't trigger a GC run that way. However, as this was an afterthought, parts of the language need to be disabled when opting out and not a lot of library functionality works with that.