So it looks like we are regularly exceeding 250k posts and comments per day although goodness knows how many of the comments are by bots. That we have around 50k daily active users and 70k posts (excluding comments) gives a better idea.
Meanwhile for comparison Facebook has
510,000 comments posted, 293,000 statuses updated (their version of a post), and 136,000 photos uploaded.
So 430k posts, and 940k posts plus comments. But wait for it, that's activity PER MINUTE. Yes FB has 4x Steemit daily volume IN ONE MINUTE. That should give you an idea of the scale of a globally popular social media platform and what a fly speck Steemit is in comparison - FB is clocking in at 5,000 times the posting activity. But hey they have a $545 billion dollar corporation behind them and STEEM is only at $1.3B as of writing. So really the are only about 10x ahead of Steemit in terms of activity per dollar.
Source: https://zephoria.com/top-15-valuable-facebook-statistics/