Agreed on pretty much the whole thing. But for more skeptical readers you will still have to address how steem activity is monetized. I don't think it's enough to say for example that payouts are given. In the case of advertising, there are large amounts of money pouring in to buy advertising. It's not as clear where money pouring into steem is for besides speculation. At the end of the day I believe it will be about two things:

1. advertising/promotion, which needs activity, as you say.
2. economy, use as a currency, etc.