Lot of reasons but mostly because you have to control the platform for most new programming languages to make sense. You want a new language on Apple platforms

Lot of reasons but mostly because you have to control the platform for most new programming languages to make sense. You want a new language on Apple platforms that isn't Swift? Good luck getting any buy-in from users. One possible path that might work is if you release your language with a framework that is great for some use case. E.g. if Qt were rewritten in some alternative language maybe that could be successful. But to create anything that polished takes a lot of time and effort, so any company is going to burn through capital just getting to a place where they can determine if they've made something users will actually switch to.