Another interesting thing here: the peak in December 2018. This is where Steemit did not create new accounts. This suggests that accounts created by others than Steemit have a higher retention rate. And we've seen this before with other analyses.
Yes I do tend to keep my alts active :)
Steem is not only about posting anymore, quite some accounts do well with playing various games on the chain.
And it's possible this trend will continue in time to come and we'll be unable to tie activity or 'still around' to posts/comments/votes.
RE: .