[tolmasky]

> Alternatives: they didn't have users?

Correct, it is well known that they kept Swift a bizarre secret internally. It seems no one thought it would be a good idea to consult with the vast swathes of engineers that had been using the language this was intended to replace for the last 30 or so years, nor to consult with the maintainers of the frameworks this language was supposedly going to help write, etc. As you can imagine, this led to many problems beyond just not getting a large enough surface area of compiler performance use cases.

Of course, after it was released, when they seemed very willing to make backward-incompatible changes for 5 years, and in theory they then had plenty of people running into this, they apparently still decided to not prioritize it.