Facebook Messenger uses React Native. WhatsApp Desktop uses WinUI. WhatsApp is superior. I don't get React Native. It's such a huge, complicated abstraction

Facebook Messenger uses React Native. WhatsApp Desktop uses WinUI. WhatsApp is superior. I don't get React Native. It's such a huge, complicated abstraction with no ability to performance tweak. I don't understand how a company as big as Facebook doesn't have enough resources to build native apps for each platform. These UIs are the simplest app you could build as well.