With JS, you have to worry way less about hardware-specific builds, platform-specific linking implications, differing system behavior and intrinsics, or any of the other substantial hangups that become relevant when you need to distribute a native application across a wide range of devices.

We don't need to repeat the rest of the thread where everyone hops in and says "tut tut, hypothetically, it would be possible for it to not be that way". We're talking about the way things actually are. In an ideal world, JS would've been out of the picture about 3 years after it was born. :)