Just an anecdote. I had a day set aside to purging my Facebook entries a year or two back. I manually deleted comments and posts.

Of course there was too many to do and it was very boring so I only spent a couple of hours at it. But that's nots what's interesting. What happened was that I got a huge uptake of people commenting on some old post I made, like a profile picture change. I think Facebook saw I was purging my data slowly and reached out to my FB contacts encouraging them to interact more with me. It was very odd.