Same applies on the memory management front, while it is understandable the decision they have made, for compatibility with Objective-C frameworks and runtime, most tracing GCs with 20+ years deployment experience are still faster than Swift on server workloads.

And it is worth remembering that Objective-C only got ARC, because adding a tracing GC was a failure, given C semantics, and most applications being prone to crashes, when the GC got pointers wrong, thus automating retain/release pairs was a much safer approach.