The reason most of the ones you mentioned went bust is a lack of ecosystem. Few and poor apps means it&#x27;s not compelling for users, which makes it unattractive for developers. I.e., if my mom can&#x27;t play Words With Friends because I buy her an Ubuntu or Sailfish phone, she&#x27;s not going to use it.<p>Firefox OS couldn&#x27;t attract WhatsApp to build an app because of lack of a user base, which put off many of their European customers who _only_ use WhatsApp for messaging. WhatsApp isn&#x27;t the only example. Even Facebook was essentially just a webview. Convincing companies to spend the resources to get onto your platform is actually really hard, and usually means developers shell out cash to companies like Facebook and WhatsApp to get them to build for their OS. You end up with this vicious feedback loop that kills the platform.<p>Android already has an ecosystem with top-of-the-line apps. If you want to build your own mobile operating system, building on Android gives you an immediate advantage because you already have developers building for your product, which means real people in the real world actually have a reason to use your phone.