[failbuffer]

Alternatively (or at least additively), most C# developers don't really need all the new ref/Span features. They're writing line-of-business apps and garbage collection is a fact of life, not some burden to be avoided.

Microsoft probably added these features to push the language into new niches (like improving the story around Unity and going after Arduino/IoT). But it's of little practical appeal to their established base.

[Dykam]

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.