I'm not tracking how your question follows. If by garbage collection you mean a system in which resources are cleaned up at or after the moment they are marked as no longer being necessary then, sure, I guess I can see a thread here, although I think it a thin connection. The conversation up-thread is about runtime garbage collectors which are a mechanism with more semantic properties than this expansive definition implies and possessing an internal complexity that is opaque to the user. An allocator does have the more expensive definition I think you might be operating with, as does a filesystem, but it's the opacity and intrinsic binding to a specific runtime GC that makes it a challenging tool for systems programming.

Go for instance bills itself as a systems language and that's true for domains where bounded, predictable memory consumption / CPU trade-offs are not necessary _because_ the runtime GC is bundled and non-negotiable. Its behavior also shifts with releases. A systems program relying on an allocator alone can choose to ignore the allocator until it's a problem and swap the implementation out for one -- perhaps custom made -- that tailors to the domain.