IMHO: Attempts to keep users engaged quite often leaves users enraged.

It’s a pattern that happens over and over again.

1. Build something cool that involves a community of users.
2. Realize that some user’s involvement is decreasing. (a totally natural occurrence)
3. Go into panic mode to try and keep users engaged. Usually by trying silly things done by other platforms.

I noticed this yesterday when Twitter tested a news article at top of news feeds. iOS users reported that they could dismiss the particular story, not sure if Android users could. I could not on Android.

You can easily measure before and after engagement and it may seem like your attempts are effective, but how do you measure how your core users now feel about your platform after annoying tactics designed to manipulate?

Before you start to build any new social platform, you should probably FIRST have an answer to this question: What will you need to do in the future to keep users engaged (and happy)?