The definition of GC encompassing RC has fallen out of favour because it doesn’t capture the essential distinctions that people want to make: firstly, are cycles broken automatically? secondly, is there any tracing process happening behind the scenes?

Most people are happy to accept that CPython is GC because it does RC and cycle collection so you are managing memory thinking about paths from a root, but not Swift because you are managing memory thinking about an ownership graph.

In the past, people wanted to make a different distinction: is the CPU having to do extra work to keep track of a reference count. When CPUs were slow, this was an important distinction to make. Nowadays it’s a less important distinction so the definition has evolved.