Because there’s no data files attached together with this setup files, they’re smaller than usual. this will help in case of slow connection.
I like this file type a lot, but be careful when you try it, read instructions on the Internet before install.
Some apps or games arent available in some regions, third party app store will be effective.
I often visit Amazon App store or http://choilieng.com to get the games i needed. They’re free of malwares.