I'm pretty sure of the same, and that feature actually leaks into the implementation. Right after the initial introduction of the current Github Actions, we translated some Azure Devops scripts to Actions and a lot of the structure and most keywords where nearly identical. As well as the interface when running the CI.
As far as I'm aware, it's the development of Kestrel which pushed the introduction of ref/Span etc. Due to it Kestrel has seen quite a large speedup, it being one of the fastest HTTP servers nowadays. ref/Span allowed them to make the core almost allocation free, together with using vectorized operations (SIMD ) for parsing the request.