This is because of two things:
- The once trigger happy phone owners have a lot of fatigue set in, with numerous notifications; at first it was like race to install all the shiny apps which came free, as if they are going to soon vaporise.
"Dobara na milega" kind of offer, people thought!
As they installed more and more apps, the lesser and lesser amount of time they spent on most of them, except the giants (FB,Twitter,WA,Tinder types and Porn) and slowly they stopped even visiting most of them.
And then when the initial low data rates started jacking up, they realised that even a dormant app is a cost in terms of data and hence money, and they started un-installing them.
Once bitten, twice shy; not sure either of the fact that people have become saner or wiser, but surely one thing they have realised is that there are only as much as 24 hours only in a day.
- Rather than anything, the app was a fad, because it gave this glorious high of residing on the users phone and hence the false notation that, it leads to maximum recall; which wiser people have realised that it is not the case now.
Web technologies has grown tremendously in all these years, and what you can on an app, you can do much better on a mobile browser, unless you want to siphon off users address book and phone call records.