Interesting times indeed :)
I've noticed that too. Since HF19 the daily number of posts has risen sharply, but the number of votes stayed the same. Here are my statistics: https://steemit.com/steemit/@penguinpablo/this-week-saw-an-increase-of-42-in-the-daily-number-of-posts
I'm not sure about the cause. I think it's due to both of the reasons you mentioned.
Oh these statistics are simply awesome, thanks for sharing the link!!!