Steem has value because it delivers outcomes irl.
Coca Cola buys up a lot of steempower to push their product, so we'll buy a can.
If Coca Cola's social media content WAS the product, they'd have no incentive to buy in and increase their reach.
That's just giving away more of their product.
The only way I could see a porn SMT working is if top end prostitutes wanted to promote their 'work' and attract 'face to face' clients.