Because Mobogenie is no longer actively supported by its original developers and has been removed from the Google Play Store due to policy violations regarding app scraping, installing it on a KitKat device today requires a manual process.
Back then, the official app stores felt restrictive. You wanted that one obscure rhythm game or a custom launcher that made your home screen look like a spaceship. So, you went looking for the APK. The Quest for the APK Free Download Mobogenie For Android 4.4.2