> Because nobody use Swift outside of iOS app development

Because that isn't true, people do use it outside of iOS app dev, and is becoming more true as time goes on to boot.

It's also a chicken-and-egg problem: no one will use Swift for non-iOS tasks if the tooling support isn't there. The more investment into it, the more it will be picked up for other tasks.

But it's been used outside of Apple-specific things since the early days in various niches.