There are a lot of reasons and they can be discussed ad-nauseum. When you boil your question down to it's essence: "Why use a first-party framework and language

There are a lot of reasons and they can be discussed ad-nauseum. When you boil your question down to it's essence: "Why use a first-party framework and language" it's much easier to answer. The simplest and most pragmatic answer is "because this is what Apple tells us to use". It's a business decision more than anything else, if your business somehow depends heavily on mobile then you want to build native apps.