Allocation pooling gets around the Go GC but is also used in non-GC languages because it can drastically reduce the overall number of allocations AND improve cache performance. In a GC lang, it also forces you to be explicit with your lifetimes which can lead to better code (i.e. you need to Pool.Put rather than let the GC clean up).

In a well designed game engine, you will only need to implement it a handful of times (if that) to cover 99% of the hot code. Certainly not something to need to do for each class of game object.