title: Why firebase is needed for android notifications along with third party notifications provider such as OneSignal, Pubnub & pusher?
body: <p>I'm working on react native push notifications. i'm looking for some answers before i make a purchase to any third party notification provider</p>
  
  <ol>
  <li>Why do third party notifications providers such as OneSignal, Pusher &amp; PubNub are based on Firebase Cloud Messaging? </li>
  <li>Can't they send notifications independently without relying on Firebase. why pay more to third party providers when FCM does the work for free? </li>
  </ol>