[InclinedPlane]

He's a game dev, says it all. The problem with GC is that often it imposes a performance overhead and, more importantly, it results in non-deterministic performance characteristics. In game dev it's typical to want to be able to complete an entire cycle of computations for calculating game mechanics within a single frame, which could be just 17 or even 7 milliseconds in entirety (60/144 fps). If you get even a fraction of a millisecond delay in computing a chunk of work that can screw up your frame rate, produce noticeable visual effects, etc.