ARC is a method of implementing garbage collection, and is discussed as such in academic literature. What you are equating with "garbage collection" is Mark-Sw

ARC is a method of implementing garbage collection, and is discussed as such in academic literature. What you are equating with "garbage collection" is Mark-Sweep, which is an another way to implement GC, with a very different set of tradeoffs. (Broadly, better throughput at the expense of higher latency.)