According to the recent announcement of Google Plus, they will be closing “App indexing feature”. They have mentioned it specifically that they will be shutting down the “Fetch As Google”. The reason they gave for this decision is that they want to avoid unnesessary duplication.
It is also predicted that soon Google will be shutting down features related to app indexing as well. Why are they doing this? There is no clear answer but later on they are focusing on AMP landing page, PWAs and some other things over mobile apps within search.
Here’s the official statement of Google
In May 2016, we announced Firebase App Indexing, together with neat testing tools for apps. To avoid unnecessary duplication, we’ll be turning off the old “Fetch As Google for Apps” feature in Search Console.
Making your apps’ content indexable has gotten much easier over the years. If you’re making smartphone apps now, please check out Firebase App Indexing at https://firebase.google.com/docs/app-indexing/ for more information.